diff --git a/Neos.Cache/Classes/Backend/AbstractBackend.php b/Neos.Cache/Classes/Backend/AbstractBackend.php
index b6ea0aa72c..05dab6c87b 100644
--- a/Neos.Cache/Classes/Backend/AbstractBackend.php
+++ b/Neos.Cache/Classes/Backend/AbstractBackend.php
@@ -61,7 +61,7 @@ abstract class AbstractBackend implements BackendInterface
      * @param array $options Configuration options - depends on the actual backend
      * @api
      */
-    public function __construct(EnvironmentConfiguration $environmentConfiguration = null, array $options = [])
+    public function __construct(?EnvironmentConfiguration $environmentConfiguration = null, array $options = [])
     {
         $this->environmentConfiguration = $environmentConfiguration;
 
@@ -144,7 +144,7 @@ public function setDefaultLifetime($defaultLifetime): void
      * @param integer $lifetime The lifetime in seconds
      * @return \DateTime The expiry time
      */
-    protected function calculateExpiryTime(int $lifetime = null): \DateTime
+    protected function calculateExpiryTime(?int $lifetime = null): \DateTime
     {
         if ($lifetime === self::UNLIMITED_LIFETIME || ($lifetime === null && $this->defaultLifetime === self::UNLIMITED_LIFETIME)) {
             return new \DateTime(self::DATETIME_EXPIRYTIME_UNLIMITED, new \DateTimeZone('UTC'));
diff --git a/Neos.Cache/Classes/Backend/ApcuBackend.php b/Neos.Cache/Classes/Backend/ApcuBackend.php
index 8b5524eb75..6d48971bef 100644
--- a/Neos.Cache/Classes/Backend/ApcuBackend.php
+++ b/Neos.Cache/Classes/Backend/ApcuBackend.php
@@ -117,7 +117,7 @@ public function getPrefixedIdentifier(string $entryIdentifier): string
      * @throws \InvalidArgumentException if the identifier is not valid
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         if (!$this->cache instanceof FrontendInterface) {
             throw new Exception('No cache frontend has been set yet via setCache().', 1232986818);
diff --git a/Neos.Cache/Classes/Backend/BackendInterface.php b/Neos.Cache/Classes/Backend/BackendInterface.php
index a7929913cf..f8b52a810e 100644
--- a/Neos.Cache/Classes/Backend/BackendInterface.php
+++ b/Neos.Cache/Classes/Backend/BackendInterface.php
@@ -57,7 +57,7 @@ public function getPrefixedIdentifier(string $entryIdentifier): string;
      * @throws \InvalidArgumentException if the identifier is not valid
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void;
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void;
 
     /**
      * Loads data from the cache.
diff --git a/Neos.Cache/Classes/Backend/FileBackend.php b/Neos.Cache/Classes/Backend/FileBackend.php
index d69b4bb824..2d6d34c954 100644
--- a/Neos.Cache/Classes/Backend/FileBackend.php
+++ b/Neos.Cache/Classes/Backend/FileBackend.php
@@ -148,7 +148,7 @@ public function setCache(FrontendInterface $cache): void
      * @throws \InvalidArgumentException
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         if ($entryIdentifier !== basename($entryIdentifier)) {
             throw new \InvalidArgumentException('The specified entry identifier must not contain a path segment.', 1282073032);
diff --git a/Neos.Cache/Classes/Backend/MemcachedBackend.php b/Neos.Cache/Classes/Backend/MemcachedBackend.php
index dacf7ce832..af6adecaa9 100644
--- a/Neos.Cache/Classes/Backend/MemcachedBackend.php
+++ b/Neos.Cache/Classes/Backend/MemcachedBackend.php
@@ -199,7 +199,7 @@ public function getPrefixedIdentifier(string $entryIdentifier): string
      * @throws \InvalidArgumentException if the identifier is not valid or the final memcached key is longer than 250 characters
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         if (strlen($this->getPrefixedIdentifier($entryIdentifier)) > 250) {
             throw new \InvalidArgumentException('Could not set value. Key more than 250 characters (' . $this->getPrefixedIdentifier($entryIdentifier) . ').', 1232969508);
diff --git a/Neos.Cache/Classes/Backend/MultiBackend.php b/Neos.Cache/Classes/Backend/MultiBackend.php
index 0346da13bf..4fc3715079 100644
--- a/Neos.Cache/Classes/Backend/MultiBackend.php
+++ b/Neos.Cache/Classes/Backend/MultiBackend.php
@@ -41,7 +41,7 @@ class MultiBackend extends AbstractBackend
     protected ?LoggerInterface $logger = null;
     protected ?ThrowableStorageInterface $throwableStorage = null;
 
-    public function __construct(EnvironmentConfiguration $environmentConfiguration = null, array $options = [])
+    public function __construct(?EnvironmentConfiguration $environmentConfiguration = null, array $options = [])
     {
         parent::__construct($environmentConfiguration, $options);
 
@@ -96,7 +96,7 @@ protected function buildSubBackend(string $backendClassName, array $backendOptio
     /**
      * @throws Throwable
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         $this->prepareBackends();
         foreach ($this->backends as $backend) {
diff --git a/Neos.Cache/Classes/Backend/NullBackend.php b/Neos.Cache/Classes/Backend/NullBackend.php
index 3cce970fde..e01c90292e 100644
--- a/Neos.Cache/Classes/Backend/NullBackend.php
+++ b/Neos.Cache/Classes/Backend/NullBackend.php
@@ -46,7 +46,7 @@ protected function setProperty(string $propertyName, $propertyValue) : bool
      * @return void
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
     }
 
diff --git a/Neos.Cache/Classes/Backend/PdoBackend.php b/Neos.Cache/Classes/Backend/PdoBackend.php
index 77a7e89244..5c772a6dc5 100644
--- a/Neos.Cache/Classes/Backend/PdoBackend.php
+++ b/Neos.Cache/Classes/Backend/PdoBackend.php
@@ -182,7 +182,7 @@ protected function setBatchSize(int $batchSize): void
      * @throws FilesException
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         $this->connect();
 
diff --git a/Neos.Cache/Classes/Backend/RedisBackend.php b/Neos.Cache/Classes/Backend/RedisBackend.php
index 27639ed7a2..329f96de5e 100644
--- a/Neos.Cache/Classes/Backend/RedisBackend.php
+++ b/Neos.Cache/Classes/Backend/RedisBackend.php
@@ -109,7 +109,7 @@ public function __construct(EnvironmentConfiguration $environmentConfiguration,
      * @throws CacheException
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         if ($this->isFrozen()) {
             throw new \RuntimeException(sprintf('Cannot add or modify cache entry because the backend of cache "%s" is frozen.', $this->cacheIdentifier), 1323344192);
@@ -493,7 +493,7 @@ public function setBatchSize(int|string $batchSize): void
         $this->batchSize = (int)$batchSize;
     }
 
-    public function setRedis(\Redis $redis = null): void
+    public function setRedis(?\Redis $redis = null): void
     {
         if ($redis !== null) {
             $this->redis = $redis;
diff --git a/Neos.Cache/Classes/Backend/SimpleFileBackend.php b/Neos.Cache/Classes/Backend/SimpleFileBackend.php
index c0173326ef..7fcef5e67c 100644
--- a/Neos.Cache/Classes/Backend/SimpleFileBackend.php
+++ b/Neos.Cache/Classes/Backend/SimpleFileBackend.php
@@ -145,7 +145,7 @@ public function getCacheDirectory(): string
      * @throws \InvalidArgumentException
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         if ($entryIdentifier !== basename($entryIdentifier)) {
             throw new \InvalidArgumentException('The specified entry identifier must not contain a path segment.', 1334756735);
@@ -493,7 +493,7 @@ protected function verifyCacheDirectory(): void
      * @param int|null $maxlen
      * @return string|false The contents of the cache file or false on error
      */
-    protected function readCacheFile(string $cacheEntryPathAndFilename, int $offset = 0, int $maxlen = null)
+    protected function readCacheFile(string $cacheEntryPathAndFilename, int $offset = 0, ?int $maxlen = null)
     {
         for ($i = 0; $i < 3; $i++) {
             $data = false;
diff --git a/Neos.Cache/Classes/Backend/TransientMemoryBackend.php b/Neos.Cache/Classes/Backend/TransientMemoryBackend.php
index 92580fe27d..1ea561187c 100644
--- a/Neos.Cache/Classes/Backend/TransientMemoryBackend.php
+++ b/Neos.Cache/Classes/Backend/TransientMemoryBackend.php
@@ -45,7 +45,7 @@ class TransientMemoryBackend extends IndependentAbstractBackend implements Tagga
      * @throws Exception if no cache frontend has been set.
      * @api
      */
-    public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
+    public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
         if (!$this->cache instanceof FrontendInterface) {
             throw new Exception('No cache frontend has been set yet via setCache().', 1238244992);
diff --git a/Neos.Cache/Classes/Frontend/FrontendInterface.php b/Neos.Cache/Classes/Frontend/FrontendInterface.php
index 8de9127f6c..18fdf62b6f 100644
--- a/Neos.Cache/Classes/Frontend/FrontendInterface.php
+++ b/Neos.Cache/Classes/Frontend/FrontendInterface.php
@@ -56,7 +56,7 @@ public function getBackend();
      * @return void
      * @api
      */
-    public function set(string $entryIdentifier, $data, array $tags = [], int $lifetime = null);
+    public function set(string $entryIdentifier, $data, array $tags = [], ?int $lifetime = null);
 
     /**
      * Finds and returns data from the cache.
diff --git a/Neos.Cache/Classes/Frontend/PhpFrontend.php b/Neos.Cache/Classes/Frontend/PhpFrontend.php
index 8a59ceb07f..c47efbab1f 100644
--- a/Neos.Cache/Classes/Frontend/PhpFrontend.php
+++ b/Neos.Cache/Classes/Frontend/PhpFrontend.php
@@ -92,7 +92,7 @@ public function getWrapped(string $entryIdentifier)
      * @throws \Neos\Cache\Exception
      * @api
      */
-    public function set(string $entryIdentifier, $sourceCode, array $tags = [], int $lifetime = null)
+    public function set(string $entryIdentifier, $sourceCode, array $tags = [], ?int $lifetime = null)
     {
         if (!$this->isValidEntryIdentifier($entryIdentifier)) {
             throw new \InvalidArgumentException('"' . $entryIdentifier . '" is not a valid cache entry identifier.', 1264023823);
diff --git a/Neos.Cache/Classes/Frontend/StringFrontend.php b/Neos.Cache/Classes/Frontend/StringFrontend.php
index 6d0a33568d..e234b57ef7 100644
--- a/Neos.Cache/Classes/Frontend/StringFrontend.php
+++ b/Neos.Cache/Classes/Frontend/StringFrontend.php
@@ -37,7 +37,7 @@ class StringFrontend extends AbstractFrontend
      * @throws \Neos\Cache\Exception
      * @api
      */
-    public function set(string $entryIdentifier, $string, array $tags = [], int $lifetime = null)
+    public function set(string $entryIdentifier, $string, array $tags = [], ?int $lifetime = null)
     {
         if (!$this->isValidEntryIdentifier($entryIdentifier)) {
             throw new \InvalidArgumentException('"' . $entryIdentifier . '" is not a valid cache entry identifier.', 1233057566);
diff --git a/Neos.Cache/Classes/Frontend/VariableFrontend.php b/Neos.Cache/Classes/Frontend/VariableFrontend.php
index 6498f081b8..01602138dc 100644
--- a/Neos.Cache/Classes/Frontend/VariableFrontend.php
+++ b/Neos.Cache/Classes/Frontend/VariableFrontend.php
@@ -56,7 +56,7 @@ public function initializeObject()
      * @throws \Neos\Cache\Exception
      * @api
      */
-    public function set(string $entryIdentifier, $variable, array $tags = [], int $lifetime = null)
+    public function set(string $entryIdentifier, $variable, array $tags = [], ?int $lifetime = null)
     {
         if (!$this->isValidEntryIdentifier($entryIdentifier)) {
             throw new \InvalidArgumentException('"' . $entryIdentifier . '" is not a valid cache entry identifier.', 1233058264);
diff --git a/Neos.Cache/Tests/Unit/Backend/SimpleFileBackendTest.php b/Neos.Cache/Tests/Unit/Backend/SimpleFileBackendTest.php
index 9d5dd33dec..96aca01355 100644
--- a/Neos.Cache/Tests/Unit/Backend/SimpleFileBackendTest.php
+++ b/Neos.Cache/Tests/Unit/Backend/SimpleFileBackendTest.php
@@ -61,7 +61,7 @@ protected function setUp(): void
      * @param FrontendInterface $mockCacheFrontend
      * @return SimpleFileBackend
      */
-    protected function getSimpleFileBackend(array $options = [], FrontendInterface $mockCacheFrontend = null)
+    protected function getSimpleFileBackend(array $options = [], ?FrontendInterface $mockCacheFrontend = null)
     {
         $simpleFileBackend = new SimpleFileBackend($this->mockEnvironmentConfiguration, $options);
 
diff --git a/Neos.Eel/Classes/Helper/ArrayHelper.php b/Neos.Eel/Classes/Helper/ArrayHelper.php
index 49f4615489..ad7936a75b 100644
--- a/Neos.Eel/Classes/Helper/ArrayHelper.php
+++ b/Neos.Eel/Classes/Helper/ArrayHelper.php
@@ -562,7 +562,7 @@ public function reduce(iterable $array, callable $callback, $initialValue = null
      * @param callable $callback Callback for testing if an element should be included in the result, current value and key will be passed as arguments
      * @return array The array with elements where callback returned true
      */
-    public function filter(iterable $array, callable $callback = null): array
+    public function filter(iterable $array, ?callable $callback = null): array
     {
         if ($array instanceof \Traversable) {
             $array = iterator_to_array($array);
diff --git a/Neos.Error.Messages/Classes/Result.php b/Neos.Error.Messages/Classes/Result.php
index 53caced03e..f0192cd5cb 100644
--- a/Neos.Error.Messages/Classes/Result.php
+++ b/Neos.Error.Messages/Classes/Result.php
@@ -132,7 +132,7 @@ public function addNotice(Notice $notice)
      * @return array<Error>
      * @api
      */
-    public function getErrors(string $messageTypeFilter = null): array
+    public function getErrors(?string $messageTypeFilter = null): array
     {
         return $this->filterMessages($this->errors, $messageTypeFilter);
     }
@@ -144,7 +144,7 @@ public function getErrors(string $messageTypeFilter = null): array
      * @return array<Warning>
      * @api
      */
-    public function getWarnings(string $messageTypeFilter = null): array
+    public function getWarnings(?string $messageTypeFilter = null): array
     {
         return $this->filterMessages($this->warnings, $messageTypeFilter);
     }
@@ -156,7 +156,7 @@ public function getWarnings(string $messageTypeFilter = null): array
      * @return array<Notice>
      * @api
      */
-    public function getNotices(string $messageTypeFilter = null): array
+    public function getNotices(?string $messageTypeFilter = null): array
     {
         return $this->filterMessages($this->notices, $messageTypeFilter);
     }
@@ -168,7 +168,7 @@ public function getNotices(string $messageTypeFilter = null): array
      * @return Error
      * @api
      */
-    public function getFirstError(string $messageTypeFilter = null)
+    public function getFirstError(?string $messageTypeFilter = null)
     {
         $matchingErrors = $this->filterMessages($this->errors, $messageTypeFilter);
         reset($matchingErrors);
@@ -182,7 +182,7 @@ public function getFirstError(string $messageTypeFilter = null)
      * @return Warning
      * @api
      */
-    public function getFirstWarning(string $messageTypeFilter = null)
+    public function getFirstWarning(?string $messageTypeFilter = null)
     {
         $matchingWarnings = $this->filterMessages($this->warnings, $messageTypeFilter);
         reset($matchingWarnings);
@@ -196,7 +196,7 @@ public function getFirstWarning(string $messageTypeFilter = null)
      * @return Notice
      * @api
      */
-    public function getFirstNotice(string $messageTypeFilter = null)
+    public function getFirstNotice(?string $messageTypeFilter = null)
     {
         $matchingNotices = $this->filterMessages($this->notices, $messageTypeFilter);
         reset($matchingNotices);
@@ -213,7 +213,7 @@ public function getFirstNotice(string $messageTypeFilter = null)
      * @return Result
      * @api
      */
-    public function forProperty(string $propertyPath = null): Result
+    public function forProperty(?string $propertyPath = null): Result
     {
         if ($propertyPath === '' || $propertyPath === null) {
             return $this;
@@ -410,7 +410,7 @@ public function getFlattenedNotices(): array
      * @param string $messageTypeFilter If specified only messages implementing the given class name are taken into account
      * @return void
      */
-    public function flattenTree(string $propertyName, array &$result, array $level = [], string $messageTypeFilter = null)
+    public function flattenTree(string $propertyName, array &$result, array $level = [], ?string $messageTypeFilter = null)
     {
         if (count($this->$propertyName) > 0) {
             $propertyPath = implode('.', $level);
@@ -429,7 +429,7 @@ public function flattenTree(string $propertyName, array &$result, array $level =
      * @param string $messageTypeFilter If specified only messages implementing the given class name are taken into account
      * @return array the filtered message instances
      */
-    protected function filterMessages(array $messages, string $messageTypeFilter = null): array
+    protected function filterMessages(array $messages, ?string $messageTypeFilter = null): array
     {
         if ($messageTypeFilter === null) {
             return $messages;
diff --git a/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php b/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
index 4c8fb9979b..5749b5df81 100644
--- a/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
@@ -83,7 +83,7 @@ public function open(): void
      * @param string $methodName
      * @return void
      */
-    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, string $packageKey = null, string $className = null, string $methodName = null): void
+    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void
     {
         if ($severity > $this->severityThreshold) {
             return;
diff --git a/Neos.Flow.Log/Classes/Backend/BackendInterface.php b/Neos.Flow.Log/Classes/Backend/BackendInterface.php
index 6ef8f3c933..a6e2646749 100644
--- a/Neos.Flow.Log/Classes/Backend/BackendInterface.php
+++ b/Neos.Flow.Log/Classes/Backend/BackendInterface.php
@@ -42,7 +42,7 @@ public function open(): void;
      * @return void
      * @api
      */
-    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, string $packageKey = null, string $className = null, string $methodName = null): void;
+    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void;
 
     /**
      * Carries out all actions necessary to cleanly close the logging backend, such as
diff --git a/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php b/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
index be461b94e1..def5dd734e 100644
--- a/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
@@ -79,7 +79,7 @@ public function open(): void
      * @return void
      * @api
      */
-    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, string $packageKey = null, string $className = null, string $methodName = null): void
+    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void
     {
         if ($severity > $this->severityThreshold) {
             return;
diff --git a/Neos.Flow.Log/Classes/Backend/FileBackend.php b/Neos.Flow.Log/Classes/Backend/FileBackend.php
index f959a6fb94..67a3ac2aaf 100644
--- a/Neos.Flow.Log/Classes/Backend/FileBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/FileBackend.php
@@ -228,7 +228,7 @@ protected function rotateLogFile(): void
      * @return void
      * @api
      */
-    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, string $packageKey = null, string $className = null, string $methodName = null): void
+    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void
     {
         if ($severity > $this->severityThreshold) {
             return;
diff --git a/Neos.Flow.Log/Classes/Backend/JsonFileBackend.php b/Neos.Flow.Log/Classes/Backend/JsonFileBackend.php
index 8484ebdfb3..d394d66274 100644
--- a/Neos.Flow.Log/Classes/Backend/JsonFileBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/JsonFileBackend.php
@@ -29,7 +29,7 @@ class JsonFileBackend extends FileBackend
      * @param string $methodName Name of the method triggering the log (determined automatically if not specified)
      * @return void
      */
-    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, string $packageKey = null, string $className = null, string $methodName = null): void
+    public function append(string $message, int $severity = LOG_INFO, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void
     {
 
         if ($severity > $this->severityThreshold) {
diff --git a/Neos.Flow.Log/Classes/Backend/NullBackend.php b/Neos.Flow.Log/Classes/Backend/NullBackend.php
index 71463bcb7f..970903d471 100644
--- a/Neos.Flow.Log/Classes/Backend/NullBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/NullBackend.php
@@ -43,7 +43,7 @@ public function open(): void
      * @return void
      * @api
      */
-    public function append(string $message, int $severity = 1, $additionalData = null, string $packageKey = null, string $className = null, string $methodName = null): void
+    public function append(string $message, int $severity = 1, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void
     {
     }
 
diff --git a/Neos.Flow/Classes/Annotations/IgnoreValidation.php b/Neos.Flow/Classes/Annotations/IgnoreValidation.php
index a3d3d8eeb9..b6e9f57970 100644
--- a/Neos.Flow/Classes/Annotations/IgnoreValidation.php
+++ b/Neos.Flow/Classes/Annotations/IgnoreValidation.php
@@ -38,7 +38,7 @@ final class IgnoreValidation
      */
     public $evaluate = false;
 
-    public function __construct(string $argumentName = null, bool $evaluate = false)
+    public function __construct(?string $argumentName = null, bool $evaluate = false)
     {
         $this->argumentName = $argumentName ? ltrim($argumentName, '$') : null;
         $this->evaluate = $evaluate;
diff --git a/Neos.Flow/Classes/Annotations/Validate.php b/Neos.Flow/Classes/Annotations/Validate.php
index 9f85537924..eccf3927db 100644
--- a/Neos.Flow/Classes/Annotations/Validate.php
+++ b/Neos.Flow/Classes/Annotations/Validate.php
@@ -47,7 +47,7 @@ final class Validate
      */
     public $validationGroups = ['Default'];
 
-    public function __construct(?string $argumentName = null, string $type = null, array $options = [], ?array $validationGroups = null)
+    public function __construct(?string $argumentName = null, ?string $type = null, array $options = [], ?array $validationGroups = null)
     {
         $this->type = $type;
 
diff --git a/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php b/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php
index 89d6615b40..e77c1eddc8 100644
--- a/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php
+++ b/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php
@@ -66,7 +66,7 @@ class AbstractAdvice implements AdviceInterface
      * @param ObjectManagerInterface $objectManager Only require if a runtime evaluations function is specified
      * @param \Closure $runtimeEvaluator Runtime evaluations function
      */
-    public function __construct(string $aspectObjectName, string $adviceMethodName, ObjectManagerInterface $objectManager = null, \Closure $runtimeEvaluator = null)
+    public function __construct(string $aspectObjectName, string $adviceMethodName, ?ObjectManagerInterface $objectManager = null, ?\Closure $runtimeEvaluator = null)
     {
         $this->aspectObjectName = $aspectObjectName;
         $this->adviceMethodName = $adviceMethodName;
diff --git a/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php b/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php
index 714890e2a6..3962d800ea 100644
--- a/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php
+++ b/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php
@@ -96,7 +96,7 @@ protected function buildArraySetupCode(array $array): string
      * @param boolean $useArgumentsArray If set, the $methodArguments array will be built from $arguments instead of using the actual parameter variables.
      * @return string The generated code to be used in an "array()" definition
      */
-    protected function buildMethodArgumentsArrayCode(string $className = null, string $methodName = null, bool $useArgumentsArray = false): string
+    protected function buildMethodArgumentsArrayCode(?string $className = null, ?string $methodName = null, bool $useArgumentsArray = false): string
     {
         if ($className === null || $methodName === null) {
             return '';
@@ -129,7 +129,7 @@ protected function buildMethodArgumentsArrayCode(string $className = null, strin
      * @param string $className Name of the class the method is declared in
      * @return string The generated parameters code
      */
-    protected function buildSavedConstructorParametersCode(string $className = null): string
+    protected function buildSavedConstructorParametersCode(?string $className = null): string
     {
         if ($className === null) {
             return '';
@@ -156,7 +156,7 @@ protected function buildSavedConstructorParametersCode(string $className = null)
      * @param string $declaringClassName Name of the declaring class. This is usually the same as the $targetClassName. However, it is the introduction interface for introduced methods.
      * @return string PHP code to be used in the method interceptor
      */
-    protected function buildAdvicesCode(array $groupedAdvices, string $methodName = null, string $targetClassName = null, string $declaringClassName = null): string
+    protected function buildAdvicesCode(array $groupedAdvices, ?string $methodName = null, ?string $targetClassName = null, ?string $declaringClassName = null): string
     {
         $advicesCode = $this->buildMethodArgumentsArrayCode($declaringClassName, $methodName, ($methodName === '__construct'));
 
diff --git a/Neos.Flow/Classes/Aop/JoinPoint.php b/Neos.Flow/Classes/Aop/JoinPoint.php
index 1ee438a8c8..dc1d6e4151 100644
--- a/Neos.Flow/Classes/Aop/JoinPoint.php
+++ b/Neos.Flow/Classes/Aop/JoinPoint.php
@@ -74,7 +74,7 @@ class JoinPoint implements JoinPointInterface
      * @param mixed $result The result of the method invocations (only used for After Returning advices)
      * @param \Exception $exception The exception thrown (only used for After Throwing advices)
      */
-    public function __construct($proxy, string $className, string $methodName, array $methodArguments, Advice\AdviceChain $adviceChain = null, $result = null, \Exception $exception = null)
+    public function __construct($proxy, string $className, string $methodName, array $methodArguments, ?Advice\AdviceChain $adviceChain = null, $result = null, ?\Exception $exception = null)
     {
         $this->proxy = $proxy;
         $this->className = $className;
diff --git a/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php b/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php
index 7b040fdfa0..7322b398d2 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php
@@ -71,7 +71,7 @@ class Pointcut implements PointcutFilterInterface
      * @param string $aspectClassName The name of the aspect class where the pointcut was declared (either explicitly or from an advice's pointcut expression)
      * @param string $pointcutMethodName (optional) If the pointcut is created from a pointcut declaration, the name of the method declaring the pointcut must be passed
      */
-    public function __construct(string $pointcutExpression, PointcutFilterComposite $pointcutFilterComposite, string $aspectClassName, string $pointcutMethodName = null)
+    public function __construct(string $pointcutExpression, PointcutFilterComposite $pointcutFilterComposite, string $aspectClassName, ?string $pointcutMethodName = null)
     {
         $this->pointcutExpression = $pointcutExpression;
         $this->pointcutFilterComposite = $pointcutFilterComposite;
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php
index bee5c15c7b..45e82c390d 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php
@@ -60,7 +60,7 @@ class PointcutMethodNameFilter implements PointcutFilterInterface
      * @param array $methodArgumentConstraints array of method constraints
      * @throws InvalidPointcutExpressionException
      */
-    public function __construct(string $methodNameFilterExpression, string $methodVisibility = null, array $methodArgumentConstraints = [])
+    public function __construct(string $methodNameFilterExpression, ?string $methodVisibility = null, array $methodArgumentConstraints = [])
     {
         $this->methodNameFilterExpression = $methodNameFilterExpression;
         if ($methodVisibility !== null && preg_match(self::PATTERN_MATCHVISIBILITYMODIFIER, $methodVisibility) !== 1) {
diff --git a/Neos.Flow/Classes/Cli/CommandController.php b/Neos.Flow/Classes/Cli/CommandController.php
index d6e509f26e..06d4b353b8 100644
--- a/Neos.Flow/Classes/Cli/CommandController.php
+++ b/Neos.Flow/Classes/Cli/CommandController.php
@@ -209,7 +209,7 @@ protected function mapRequestArgumentsToControllerArguments()
      * @return void
      * @throws StopCommandException
      */
-    protected function forward(string $commandName, string $controllerObjectName = null, array $arguments = [])
+    protected function forward(string $commandName, ?string $controllerObjectName = null, array $arguments = [])
     {
         $this->request->setDispatched(false);
         $this->request->setControllerCommandName($commandName);
diff --git a/Neos.Flow/Classes/Cli/ConsoleOutput.php b/Neos.Flow/Classes/Cli/ConsoleOutput.php
index 8fb93661a4..f5752b6b27 100644
--- a/Neos.Flow/Classes/Cli/ConsoleOutput.php
+++ b/Neos.Flow/Classes/Cli/ConsoleOutput.php
@@ -140,7 +140,7 @@ public function outputFormatted(string $text = '', array $arguments = [], int $l
      * @param array $headers
      * @param string $headerTitle
      */
-    public function outputTable(array $rows, array $headers = null, string $headerTitle = null): void
+    public function outputTable(array $rows, ?array $headers = null, ?string $headerTitle = null): void
     {
         $table = $this->getTable();
         if ($headers !== null) {
@@ -164,7 +164,7 @@ public function outputTable(array $rows, array $headers = null, string $headerTi
      * @return integer|string|array Either the value for indexed arrays, the key for associative arrays or an array for multiple selections
      * @throws \InvalidArgumentException
      */
-    public function select($question, array $choices, $default = null, bool $multiSelect = false, int $attempts = null)
+    public function select($question, array $choices, $default = null, bool $multiSelect = false, ?int $attempts = null)
     {
         $question = new ChoiceQuestion($this->combineQuestion($question), $choices, $default);
         $question
@@ -183,7 +183,7 @@ public function select($question, array $choices, $default = null, bool $multiSe
      * @return mixed The user answer
      * @throws \RuntimeException If there is no data to read in the input stream
      */
-    public function ask($question, string $default = null)
+    public function ask($question, ?string $default = null)
     {
         $question = new Question($this->combineQuestion($question), $default);
 
@@ -251,7 +251,7 @@ public function askHiddenResponse($question, bool $fallback = true)
      * @return mixed The response
      * @throws \Exception When any of the validators return an error
      */
-    public function askAndValidate($question, callable $validator, int $attempts = null, string $default = null)
+    public function askAndValidate($question, callable $validator, ?int $attempts = null, ?string $default = null)
     {
         $question = new Question($this->combineQuestion($question), $default);
         $question
@@ -276,7 +276,7 @@ public function askAndValidate($question, callable $validator, int $attempts = n
      * @throws \Exception When any of the validators return an error
      * @throws \RuntimeException In case the fallback is deactivated and the response can not be hidden
      */
-    public function askHiddenResponseAndValidate($question, callable $validator, int $attempts = null, bool $fallback = true)
+    public function askHiddenResponseAndValidate($question, callable $validator, ?int $attempts = null, bool $fallback = true)
     {
         $question = new Question($this->combineQuestion($question));
         $question
@@ -294,7 +294,7 @@ public function askHiddenResponseAndValidate($question, callable $validator, int
      * @param integer $max Maximum steps. If NULL an indeterminate progress bar is rendered
      * @return void
      */
-    public function progressStart(int $max = null): void
+    public function progressStart(?int $max = null): void
     {
         $this->getProgressBar()->start($max);
     }
diff --git a/Neos.Flow/Classes/Command/CacheCommandController.php b/Neos.Flow/Classes/Command/CacheCommandController.php
index 776753b21d..9782466b81 100644
--- a/Neos.Flow/Classes/Command/CacheCommandController.php
+++ b/Neos.Flow/Classes/Command/CacheCommandController.php
@@ -430,7 +430,7 @@ public function setupAllCommand(bool $quiet = false)
      * @return void
      * @throws NoSuchCacheException
      */
-    public function collectGarbageCommand(string $cacheIdentifier = null): void
+    public function collectGarbageCommand(?string $cacheIdentifier = null): void
     {
         if ($cacheIdentifier !== null) {
             $cache = $this->cacheManager->getCache($cacheIdentifier);
diff --git a/Neos.Flow/Classes/Command/ConfigurationCommandController.php b/Neos.Flow/Classes/Command/ConfigurationCommandController.php
index 801b3aa6cc..79a68a74a9 100644
--- a/Neos.Flow/Classes/Command/ConfigurationCommandController.php
+++ b/Neos.Flow/Classes/Command/ConfigurationCommandController.php
@@ -64,7 +64,7 @@ class ConfigurationCommandController extends CommandController
      * @param string $path path to subconfiguration separated by "." like "Neos.Flow"
      * @return void
      */
-    public function showCommand(string $type = 'Settings', string $path = null)
+    public function showCommand(string $type = 'Settings', ?string $path = null)
     {
         $availableConfigurationTypes = $this->configurationManager->getAvailableConfigurationTypes();
         if (in_array($type, $availableConfigurationTypes)) {
@@ -125,7 +125,7 @@ public function listTypesCommand()
      * @param boolean $verbose if true, output more verbose information on the schema files which were used
      * @return void
      */
-    public function validateCommand(string $type = null, string $path = null, bool $verbose = false)
+    public function validateCommand(?string $type = null, ?string $path = null, bool $verbose = false)
     {
         if ($type === null) {
             $this->outputLine('Validating <b>all</b> configuration');
@@ -188,7 +188,7 @@ public function validateCommand(string $type = null, string $path = null, bool $
      * @param string $yaml YAML file to create a schema for
      * @return void
      */
-    public function generateSchemaCommand(string $type = null, string $path = null, string $yaml = null)
+    public function generateSchemaCommand(?string $type = null, ?string $path = null, ?string $yaml = null)
     {
         $data = null;
         if ($yaml !== null && is_file($yaml) && is_readable($yaml)) {
diff --git a/Neos.Flow/Classes/Command/CoreCommandController.php b/Neos.Flow/Classes/Command/CoreCommandController.php
index b0e285267c..4e1607e0e8 100644
--- a/Neos.Flow/Classes/Command/CoreCommandController.php
+++ b/Neos.Flow/Classes/Command/CoreCommandController.php
@@ -257,7 +257,7 @@ public function setFilePermissionsCommand(string $commandlineUser, string $webse
      * @return void
      * @see neos.flow:doctrine:migrate
      */
-    public function migrateCommand(string $package, bool $status = false, string $packagesPath = null, string $version = null, bool $verbose = false, bool $force = false)
+    public function migrateCommand(string $package, bool $status = false, ?string $packagesPath = null, ?string $version = null, bool $verbose = false, bool $force = false)
     {
         // This command will never be really called. It rather acts as a stub for rendering the
         // documentation for this command. In reality, the "flow" command line script will already
diff --git a/Neos.Flow/Classes/Command/DatabaseCommandController.php b/Neos.Flow/Classes/Command/DatabaseCommandController.php
index 1a9e435de8..87fc9e756c 100644
--- a/Neos.Flow/Classes/Command/DatabaseCommandController.php
+++ b/Neos.Flow/Classes/Command/DatabaseCommandController.php
@@ -86,7 +86,7 @@ protected function initializeConnection()
      * @throws DBALException
      * @throws StopActionException
      */
-    public function setCharsetCommand(string $characterSet = 'utf8mb4', string $collation = 'utf8mb4_unicode_ci', string $output = null, bool $verbose = false)
+    public function setCharsetCommand(string $characterSet = 'utf8mb4', string $collation = 'utf8mb4_unicode_ci', ?string $output = null, bool $verbose = false)
     {
         if (!in_array($this->persistenceSettings['backendOptions']['driver'], ['pdo_mysql', 'mysqli'])) {
             $this->outputLine('Database charset/collation fixing is only supported on MySQL.');
@@ -118,7 +118,7 @@ public function setCharsetCommand(string $characterSet = 'utf8mb4', string $coll
      * @throws ConnectionException
      * @throws DBALException
      */
-    protected function convertToCharacterSetAndCollation(string $characterSet, string $collation, string $outputPathAndFilename = null, bool $verbose = false)
+    protected function convertToCharacterSetAndCollation(string $characterSet, string $collation, ?string $outputPathAndFilename = null, bool $verbose = false)
     {
         $statements = ['SET foreign_key_checks = 0'];
 
diff --git a/Neos.Flow/Classes/Command/DoctrineCommandController.php b/Neos.Flow/Classes/Command/DoctrineCommandController.php
index 899be0ea9f..dd9949a9ba 100644
--- a/Neos.Flow/Classes/Command/DoctrineCommandController.php
+++ b/Neos.Flow/Classes/Command/DoctrineCommandController.php
@@ -144,7 +144,7 @@ public function validateCommand(): void
      * @see neos.flow:doctrine:update
      * @see neos.flow:doctrine:migrate
      */
-    public function createCommand(string $output = null): void
+    public function createCommand(?string $output = null): void
     {
         if (!$this->isDatabaseConfigured()) {
             $this->outputLine('Database schema creation has been SKIPPED, the driver and host backend options are not set in /Configuration/Settings.yaml.');
@@ -173,7 +173,7 @@ public function createCommand(string $output = null): void
      * @see neos.flow:doctrine:create
      * @see neos.flow:doctrine:migrate
      */
-    public function updateCommand(bool $unsafeMode = false, string $output = null): void
+    public function updateCommand(bool $unsafeMode = false, ?string $output = null): void
     {
         if (!$this->isDatabaseConfigured()) {
             $this->outputLine('Database schema update has been SKIPPED, the driver and host backend options are not set in /Configuration/Settings.yaml.');
@@ -202,7 +202,7 @@ public function updateCommand(bool $unsafeMode = false, string $output = null):
      * @throws \Doctrine\ORM\ORMException
      * @see neos.flow:doctrine:validate
      */
-    public function entityStatusCommand(bool $dumpMappingData = false, string $entityClassName = null): void
+    public function entityStatusCommand(bool $dumpMappingData = false, ?string $entityClassName = null): void
     {
         $info = $this->doctrineService->getEntityStatus();
 
@@ -255,7 +255,7 @@ public function entityStatusCommand(bool $dumpMappingData = false, string $entit
      * @return void
      * @throws StopCommandException
      */
-    public function dqlCommand(int $depth = 3, string $hydrationMode = 'array', int $offset = null, int $limit = null): void
+    public function dqlCommand(int $depth = 3, string $hydrationMode = 'array', ?int $offset = null, ?int $limit = null): void
     {
         if (!$this->isDatabaseConfigured()) {
             $this->outputLine('DQL query is not possible, the driver and host backend options are not set in /Configuration/Settings.yaml.');
@@ -316,7 +316,7 @@ public function migrationStatusCommand(bool $showMigrations = false): void
      * @see neos.flow:doctrine:migrationgenerate
      * @see neos.flow:doctrine:migrationversion
      */
-    public function migrateCommand(string $version = 'latest', string $output = null, bool $dryRun = false, bool $quiet = false): void
+    public function migrateCommand(string $version = 'latest', ?string $output = null, bool $dryRun = false, bool $quiet = false): void
     {
         if (!$this->isDatabaseConfigured()) {
             $this->outputLine('Doctrine migration not possible, the driver and host backend options are not set in /Configuration/Settings.yaml.');
@@ -363,7 +363,7 @@ protected function emitAfterDatabaseMigration(): void
      * @see neos.flow:doctrine:migrationgenerate
      * @see neos.flow:doctrine:migrationversion
      */
-    public function migrationExecuteCommand(string $version, string $direction = 'up', string $output = null, bool $dryRun = false): void
+    public function migrationExecuteCommand(string $version, string $direction = 'up', ?string $output = null, bool $dryRun = false): void
     {
         if (!$this->isDatabaseConfigured()) {
             $this->outputLine('Doctrine migration not possible, the driver and host backend options are not set in /Configuration/Settings.yaml.');
@@ -448,7 +448,7 @@ public function migrationVersionCommand(string $version, bool $add = false, bool
      * @see neos.flow:doctrine:migrationexecute
      * @see neos.flow:doctrine:migrationversion
      */
-    public function migrationGenerateCommand(bool $diffAgainstCurrent = true, string $filterExpression = null, bool $force = false): void
+    public function migrationGenerateCommand(bool $diffAgainstCurrent = true, ?string $filterExpression = null, bool $force = false): void
     {
         if (!$this->isDatabaseConfigured()) {
             $this->outputLine('Doctrine migration generation has been SKIPPED, the driver and host backend options are not set in /Configuration/Settings.yaml.');
diff --git a/Neos.Flow/Classes/Command/HelpCommandController.php b/Neos.Flow/Classes/Command/HelpCommandController.php
index 924c6670a8..5127b5132f 100644
--- a/Neos.Flow/Classes/Command/HelpCommandController.php
+++ b/Neos.Flow/Classes/Command/HelpCommandController.php
@@ -82,7 +82,7 @@ public function helpStubCommand()
      * @return void
      * @throws StopActionException
      */
-    public function helpCommand(string $commandIdentifier = null)
+    public function helpCommand(?string $commandIdentifier = null)
     {
         $exceedingArguments = $this->request->getExceedingArguments();
         if (count($exceedingArguments) > 0 && $commandIdentifier === null) {
diff --git a/Neos.Flow/Classes/Command/ResourceCommandController.php b/Neos.Flow/Classes/Command/ResourceCommandController.php
index dcb2ec7b95..000c07fcd8 100644
--- a/Neos.Flow/Classes/Command/ResourceCommandController.php
+++ b/Neos.Flow/Classes/Command/ResourceCommandController.php
@@ -78,7 +78,7 @@ class ResourceCommandController extends CommandController
      * @param string $collection If specified, only resources of this collection are published. Example: 'persistent'
      * @return void
      */
-    public function publishCommand(string $collection = null)
+    public function publishCommand(?string $collection = null)
     {
         try {
             if ($collection === null) {
diff --git a/Neos.Flow/Classes/Command/RoutingCommandController.php b/Neos.Flow/Classes/Command/RoutingCommandController.php
index acb33fe95c..5c8e1cc985 100644
--- a/Neos.Flow/Classes/Command/RoutingCommandController.php
+++ b/Neos.Flow/Classes/Command/RoutingCommandController.php
@@ -168,7 +168,7 @@ public function getPathCommand(string $package, string $controller = 'Standard',
      * @return void
      * @throws StopCommandException | InvalidRoutePartValueException
      */
-    public function resolveCommand(string $package, string $controller = null, string $action = null, string $format = null, string $subpackage = null, string $additionalArguments = null, string $parameters = null, string $baseUri = null, bool $forceAbsoluteUri = null): void
+    public function resolveCommand(string $package, ?string $controller = null, ?string $action = null, ?string $format = null, ?string $subpackage = null, ?string $additionalArguments = null, ?string $parameters = null, ?string $baseUri = null, ?bool $forceAbsoluteUri = null): void
     {
         $routeValues = [
             '@package' => $package,
@@ -266,7 +266,7 @@ public function routePathCommand(string $path, string $method = 'GET'): void
      * @param string|null $parameters Route parameters as JSON string. Make sure to specify this option as described in the description in order to prevent parsing issues
      * @throws InvalidRoutePartValueException | StopCommandException
      */
-    public function matchCommand(string $uri, string $method = null, string $parameters = null): void
+    public function matchCommand(string $uri, ?string $method = null, ?string $parameters = null): void
     {
         $method = $method ?? 'GET';
         $requestUri = new Uri($uri);
diff --git a/Neos.Flow/Classes/Command/SchemaCommandController.php b/Neos.Flow/Classes/Command/SchemaCommandController.php
index de65a5026a..18a869784c 100644
--- a/Neos.Flow/Classes/Command/SchemaCommandController.php
+++ b/Neos.Flow/Classes/Command/SchemaCommandController.php
@@ -46,7 +46,7 @@ class SchemaCommandController extends CommandController
      * @param boolean $verbose if true, output more verbose information on the schema files which were used
      * @return void
      */
-    public function validateCommand(string $configurationFile = null, string $schemaFile = 'resource://Neos.Flow/Private/Schema/Schema.schema.yaml', bool $verbose = false)
+    public function validateCommand(?string $configurationFile = null, string $schemaFile = 'resource://Neos.Flow/Private/Schema/Schema.schema.yaml', bool $verbose = false)
     {
         $this->outputLine('Validating <b>' . $configurationFile . '</b> with schema  <b>' . $schemaFile . '</b>');
         $this->outputLine();
diff --git a/Neos.Flow/Classes/Command/SignalCommandController.php b/Neos.Flow/Classes/Command/SignalCommandController.php
index b6aa8d0749..3c2633d0f3 100644
--- a/Neos.Flow/Classes/Command/SignalCommandController.php
+++ b/Neos.Flow/Classes/Command/SignalCommandController.php
@@ -37,7 +37,7 @@ class SignalCommandController extends CommandController
      * @param string $methodName if specified, only signals matching the given method name will be shown. This is only useful in conjunction with the "--class-name" option.
      * @return void
      */
-    public function listConnectedCommand(string $className = null, string $methodName = null): void
+    public function listConnectedCommand(?string $className = null, ?string $methodName = null): void
     {
         $this->outputFormatted('<b>Connected signals with their slots.</b>');
         $this->outputLine();
diff --git a/Neos.Flow/Classes/Command/TypeConverterCommandController.php b/Neos.Flow/Classes/Command/TypeConverterCommandController.php
index c31b1bd079..bd597c0c3e 100644
--- a/Neos.Flow/Classes/Command/TypeConverterCommandController.php
+++ b/Neos.Flow/Classes/Command/TypeConverterCommandController.php
@@ -38,7 +38,7 @@ class TypeConverterCommandController extends CommandController
      * @param string $target Filter by target type
      * @return void
      */
-    public function listCommand(string $source = null, string $target = null)
+    public function listCommand(?string $source = null, ?string $target = null)
     {
         $this->outputLine();
         if ($source !== null) {
diff --git a/Neos.Flow/Classes/Composer/ComposerUtility.php b/Neos.Flow/Classes/Composer/ComposerUtility.php
index 94cca5a9ab..7a3e794153 100644
--- a/Neos.Flow/Classes/Composer/ComposerUtility.php
+++ b/Neos.Flow/Classes/Composer/ComposerUtility.php
@@ -43,7 +43,7 @@ class ComposerUtility
      * @param string $configurationPath Optional. Only return the part of the manifest indexed by configurationPath
      * @return array|mixed
      */
-    public static function getComposerManifest(string $manifestPath, string $configurationPath = null)
+    public static function getComposerManifest(string $manifestPath, ?string $configurationPath = null)
     {
         $composerManifest = static::readComposerManifest($manifestPath);
         if ($composerManifest === null) {
diff --git a/Neos.Flow/Classes/Configuration/ConfigurationManager.php b/Neos.Flow/Classes/Configuration/ConfigurationManager.php
index 6c90100f4c..a9d0c092f8 100644
--- a/Neos.Flow/Classes/Configuration/ConfigurationManager.php
+++ b/Neos.Flow/Classes/Configuration/ConfigurationManager.php
@@ -288,7 +288,7 @@ protected function emitConfigurationManagerReady(ConfigurationManager $configura
      * @return mixed The configuration or NULL if the configuration doesn't exist
      * @throws Exception\InvalidConfigurationTypeException on invalid configuration types
      */
-    public function getConfiguration(string $configurationType, string $configurationPath = null)
+    public function getConfiguration(string $configurationType, ?string $configurationPath = null)
     {
         if (empty($this->configurations[$configurationType])) {
             $this->loadConfiguration($configurationType, $this->packages);
@@ -468,7 +468,7 @@ protected function saveConfigurationCache(): void
      *
      * @param string $cachePathAndFilename The file to save the cache
      */
-    protected function writeConfigurationCacheFile(string $cachePathAndFilename, string $configurationType = null): void
+    protected function writeConfigurationCacheFile(string $cachePathAndFilename, ?string $configurationType = null): void
     {
         if (!file_exists(dirname($cachePathAndFilename))) {
             Files::createDirectoryRecursively(dirname($cachePathAndFilename));
diff --git a/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php b/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php
index ed24c65d13..f932acf70b 100644
--- a/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php
+++ b/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php
@@ -70,7 +70,7 @@ class ConfigurationSchemaValidator
      * @return \Neos\Error\Messages\Result the result of the validation
      * @throws Exception\SchemaValidationException
      */
-    public function validate(string $configurationType = null, string $path = null, array &$loadedSchemaFiles = []): Result
+    public function validate(?string $configurationType = null, ?string $path = null, array &$loadedSchemaFiles = []): Result
     {
         if ($configurationType === null) {
             $configurationTypes = $this->configurationManager->getAvailableConfigurationTypes();
@@ -95,7 +95,7 @@ public function validate(string $configurationType = null, string $path = null,
      * @return \Neos\Error\Messages\Result
      * @throws Exception\SchemaValidationException
      */
-    protected function validateSingleType(string $configurationType, string $path = null, array&$loadedSchemaFiles = []): Result
+    protected function validateSingleType(string $configurationType, ?string $path = null, array&$loadedSchemaFiles = []): Result
     {
         $availableConfigurationTypes = $this->configurationManager->getAvailableConfigurationTypes();
         if (in_array($configurationType, $availableConfigurationTypes) === false) {
diff --git a/Neos.Flow/Classes/Core/Booting/Scripts.php b/Neos.Flow/Classes/Core/Booting/Scripts.php
index c96c22c46b..d8eb41b6cd 100644
--- a/Neos.Flow/Classes/Core/Booting/Scripts.php
+++ b/Neos.Flow/Classes/Core/Booting/Scripts.php
@@ -637,7 +637,7 @@ protected static function getListOfPackagesWithConfiguredObjects(Bootstrap $boot
      * @param string $filenamePattern Optional pattern for filenames to consider for file monitoring (regular expression). @see FileMonitor::monitorDirectory()
      * @return void
      */
-    protected static function monitorDirectoryIfItExists(FileMonitor $fileMonitor, string $path, string $filenamePattern = null)
+    protected static function monitorDirectoryIfItExists(FileMonitor $fileMonitor, string $path, ?string $filenamePattern = null)
     {
         if (is_dir($path)) {
             $fileMonitor->monitorDirectory($path, $filenamePattern);
diff --git a/Neos.Flow/Classes/Core/Bootstrap.php b/Neos.Flow/Classes/Core/Bootstrap.php
index 565f5a440f..72975048a8 100644
--- a/Neos.Flow/Classes/Core/Bootstrap.php
+++ b/Neos.Flow/Classes/Core/Bootstrap.php
@@ -82,7 +82,7 @@ class Bootstrap
      * @param string $context The application context, for example "Production" or "Development"
      * @param \Composer\Autoload\ClassLoader $composerAutoloader Composer autoloader
      */
-    public function __construct(string $context, \Composer\Autoload\ClassLoader $composerAutoloader = null)
+    public function __construct(string $context, ?\Composer\Autoload\ClassLoader $composerAutoloader = null)
     {
         // Load the composer autoloader first if not provided
         $composerAutoloader = $composerAutoloader ?? require(__DIR__ . '/../../../../Libraries/autoload.php');
diff --git a/Neos.Flow/Classes/Core/ProxyClassLoader.php b/Neos.Flow/Classes/Core/ProxyClassLoader.php
index 601faccd4d..350b642ba9 100644
--- a/Neos.Flow/Classes/Core/ProxyClassLoader.php
+++ b/Neos.Flow/Classes/Core/ProxyClassLoader.php
@@ -106,7 +106,7 @@ public function loadClass($className)
      * @param ApplicationContext $context
      * @return void
      */
-    public function initializeAvailableProxyClasses(ApplicationContext $context = null)
+    public function initializeAvailableProxyClasses(?ApplicationContext $context = null)
     {
         if ($context === null) {
             return;
diff --git a/Neos.Flow/Classes/Error/Debugger.php b/Neos.Flow/Classes/Error/Debugger.php
index 83f845d6c9..7c55f88f80 100644
--- a/Neos.Flow/Classes/Error/Debugger.php
+++ b/Neos.Flow/Classes/Error/Debugger.php
@@ -606,7 +606,7 @@ public static function getRecursionLimit(): int
  * @return void|string if $return is true, the variable dump is returned. By default, the dump is directly displayed, and nothing is returned.
  * @api
  */
-function var_dump($variable, string $title = null, bool $return = false, bool $plaintext = null)
+function var_dump($variable, ?string $title = null, bool $return = false, ?bool $plaintext = null)
 {
     if ($plaintext === null) {
         $plaintext = (FLOW_SAPITYPE === 'CLI');
diff --git a/Neos.Flow/Classes/Http/BaseUriProvider.php b/Neos.Flow/Classes/Http/BaseUriProvider.php
index 22ea717d62..a66271dfe2 100644
--- a/Neos.Flow/Classes/Http/BaseUriProvider.php
+++ b/Neos.Flow/Classes/Http/BaseUriProvider.php
@@ -75,7 +75,7 @@ private function generateBaseUriFromHttpRequest(): ?UriInterface
      * @return UriInterface
      * @throws Exception
      */
-    public function getConfiguredBaseUriOrFallbackToCurrentRequest(ServerRequestInterface $fallbackRequest = null): UriInterface
+    public function getConfiguredBaseUriOrFallbackToCurrentRequest(?ServerRequestInterface $fallbackRequest = null): UriInterface
     {
         $baseUri = $this->getConfiguredBaseUri();
         if ($baseUri instanceof UriInterface) {
diff --git a/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php b/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php
index fc393bf47f..7473fbe76b 100644
--- a/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php
+++ b/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php
@@ -68,7 +68,7 @@ public static function upcastUploadedFiles(array $uploadedFiles, array $argument
      * @param string $collectionName
      * @return FlowUploadedFile
      */
-    protected static function upcastUploadedFile(UploadedFileInterface $uploadedFile, $originallySubmittedResource = null, string $collectionName = null): FlowUploadedFile
+    protected static function upcastUploadedFile(UploadedFileInterface $uploadedFile, $originallySubmittedResource = null, ?string $collectionName = null): FlowUploadedFile
     {
         // If upload failed, just accessing the stream will throwin guzzle
         $stream = $uploadedFile->getError() === UPLOAD_ERR_OK ? $uploadedFile->getStream() : Utils::streamFor(null);
@@ -128,7 +128,7 @@ public static function untangleFilesArray(array $convolutedFiles): array
      * @param string $firstLevelFieldName
      * @return array An array of paths (as arrays) in the format ["key1", "key2", "key3"] ...
      */
-    protected static function calculateFieldPathsAsArray(array $structure, string $firstLevelFieldName = null): array
+    protected static function calculateFieldPathsAsArray(array $structure, ?string $firstLevelFieldName = null): array
     {
         $fieldPaths = [];
         foreach ($structure as $key => $subStructure) {
diff --git a/Neos.Flow/Classes/I18n/FormatResolver.php b/Neos.Flow/Classes/I18n/FormatResolver.php
index 6a77ff2318..c9ab23df2b 100644
--- a/Neos.Flow/Classes/I18n/FormatResolver.php
+++ b/Neos.Flow/Classes/I18n/FormatResolver.php
@@ -98,7 +98,7 @@ public function injectLocalizationService(I18n\Service $localizationService)
      * @throws Exception\IndexOutOfBoundsException When trying to format nonexistent value
      * @api
      */
-    public function resolvePlaceholders($textWithPlaceholders, array $arguments, Locale $locale = null)
+    public function resolvePlaceholders($textWithPlaceholders, array $arguments, ?Locale $locale = null)
     {
         if ($locale === null) {
             $locale = $this->localizationService->getConfiguration()->getDefaultLocale();
diff --git a/Neos.Flow/Classes/I18n/LocaleTypeConverter.php b/Neos.Flow/Classes/I18n/LocaleTypeConverter.php
index f176815432..3782097561 100644
--- a/Neos.Flow/Classes/I18n/LocaleTypeConverter.php
+++ b/Neos.Flow/Classes/I18n/LocaleTypeConverter.php
@@ -48,7 +48,7 @@ class LocaleTypeConverter extends AbstractTypeConverter
      * @return Locale
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return new Locale($source);
     }
diff --git a/Neos.Flow/Classes/I18n/Service.php b/Neos.Flow/Classes/I18n/Service.php
index ecf293c180..43d366c038 100644
--- a/Neos.Flow/Classes/I18n/Service.php
+++ b/Neos.Flow/Classes/I18n/Service.php
@@ -124,7 +124,7 @@ public function getConfiguration()
      * @see Configuration::setFallbackRule()
      * @api
      */
-    public function getLocalizedFilename($pathAndFilename, Locale $locale = null, $strict = false)
+    public function getLocalizedFilename($pathAndFilename, ?Locale $locale = null, $strict = false)
     {
         if ($locale === null) {
             $locale = $this->configuration->getCurrentLocale();
@@ -177,7 +177,7 @@ public function getLocalizedFilename($pathAndFilename, Locale $locale = null, $s
      * @see Configuration::setFallbackRule()
      * @api
      */
-    public function getXliffFilenameAndPath($path, $sourceName, Locale $locale = null)
+    public function getXliffFilenameAndPath($path, $sourceName, ?Locale $locale = null)
     {
         if ($locale === null) {
             $locale = $this->configuration->getCurrentLocale();
diff --git a/Neos.Flow/Classes/I18n/Translator.php b/Neos.Flow/Classes/I18n/Translator.php
index 5bab4c06c2..c4938afddd 100644
--- a/Neos.Flow/Classes/I18n/Translator.php
+++ b/Neos.Flow/Classes/I18n/Translator.php
@@ -123,7 +123,7 @@ public function injectPluralsReader(Cldr\Reader\PluralsReader $pluralsReader)
      * @throws Exception\InvalidFormatPlaceholderException
      * @api
      */
-    public function translateByOriginalLabel($originalLabel, array $arguments = [], $quantity = null, Locale $locale = null, string $sourceName = 'Main', string $packageKey = 'Neos.Flow')
+    public function translateByOriginalLabel($originalLabel, array $arguments = [], $quantity = null, ?Locale $locale = null, string $sourceName = 'Main', string $packageKey = 'Neos.Flow')
     {
         if ($locale === null) {
             $locale = $this->localizationService->getConfiguration()->getCurrentLocale();
@@ -181,7 +181,7 @@ public function translateByOriginalLabel($originalLabel, array $arguments = [],
      * @api
      * @see Translator::translateByOriginalLabel()
      */
-    public function translateById($labelId, array $arguments = [], $quantity = null, Locale $locale = null, $sourceName = 'Main', $packageKey = 'Neos.Flow')
+    public function translateById($labelId, array $arguments = [], $quantity = null, ?Locale $locale = null, $sourceName = 'Main', $packageKey = 'Neos.Flow')
     {
         if ($locale === null) {
             $locale = $this->localizationService->getConfiguration()->getCurrentLocale();
diff --git a/Neos.Flow/Classes/Mvc/RequestMatcher.php b/Neos.Flow/Classes/Mvc/RequestMatcher.php
index 07420f05fe..a82b8e5050 100644
--- a/Neos.Flow/Classes/Mvc/RequestMatcher.php
+++ b/Neos.Flow/Classes/Mvc/RequestMatcher.php
@@ -61,7 +61,7 @@ class RequestMatcher
      * @param ActionRequest $actionRequest
      * @param RequestMatcher $parentMatcher
      */
-    public function __construct(ActionRequest $actionRequest = null, $parentMatcher = null)
+    public function __construct(?ActionRequest $actionRequest = null, $parentMatcher = null)
     {
         $this->request = $actionRequest;
         $this->parentMatcher = $parentMatcher;
diff --git a/Neos.Flow/Classes/Mvc/Routing/Dto/MatchResult.php b/Neos.Flow/Classes/Mvc/Routing/Dto/MatchResult.php
index c775fd4567..5c3a9e71d8 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Dto/MatchResult.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Dto/MatchResult.php
@@ -39,7 +39,7 @@ final class MatchResult
      * @param mixed $matchedValue
      * @param RouteTags $tags
      */
-    public function __construct($matchedValue, RouteTags $tags = null, RouteLifetime $lifetime = null)
+    public function __construct($matchedValue, ?RouteTags $tags = null, ?RouteLifetime $lifetime = null)
     {
         $this->matchedValue = $matchedValue;
         $this->tags = $tags;
diff --git a/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveResult.php b/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveResult.php
index d13bef5fde..a2702ba7a1 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveResult.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveResult.php
@@ -53,7 +53,7 @@ final class ResolveResult
      * @param UriConstraints $uriConstraints
      * @param RouteTags $tags
      */
-    public function __construct(string $resolvedValue, UriConstraints $uriConstraints = null, RouteTags $tags = null, RouteLifetime $lifetime = null)
+    public function __construct(string $resolvedValue, ?UriConstraints $uriConstraints = null, ?RouteTags $tags = null, ?RouteLifetime $lifetime = null)
     {
         $this->resolvedValue = $resolvedValue;
         $this->uriConstraints = $uriConstraints;
diff --git a/Neos.Flow/Classes/Mvc/Routing/Router.php b/Neos.Flow/Classes/Mvc/Routing/Router.php
index 44e431b39c..1c568b4b09 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Router.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Router.php
@@ -100,7 +100,7 @@ public function injectLogger(LoggerInterface $logger)
      * @param array $routesConfiguration The routes configuration or NULL if it should be fetched from configuration
      * @return void
      */
-    public function setRoutesConfiguration(array $routesConfiguration = null)
+    public function setRoutesConfiguration(?array $routesConfiguration = null)
     {
         $this->routesConfiguration = $routesConfiguration;
         $this->routesCreated = false;
diff --git a/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php b/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php
index d6658810db..01af7f5b40 100644
--- a/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php
+++ b/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php
@@ -114,7 +114,7 @@ public function getCachedMatchResults(RouteContext $routeContext)
      * @param RouteLifetime|null $matchedLifetime
      * @return void
      */
-    public function storeMatchResults(RouteContext $routeContext, array $matchResults, RouteTags $matchedTags = null, RouteLifetime $matchedLifetime = null)
+    public function storeMatchResults(RouteContext $routeContext, array $matchResults, ?RouteTags $matchedTags = null, ?RouteLifetime $matchedLifetime = null)
     {
         if ($this->containsObject($matchResults)) {
             return;
@@ -152,7 +152,7 @@ public function getCachedResolvedUriConstraints(ResolveContext $resolveContext)
      * @param RouteLifetime|null $resolvedLifetime
      * @return void
      */
-    public function storeResolvedUriConstraints(ResolveContext $resolveContext, UriConstraints $uriConstraints, RouteTags $resolvedTags = null, RouteLifetime $resolvedLifetime = null)
+    public function storeResolvedUriConstraints(ResolveContext $resolveContext, UriConstraints $uriConstraints, ?RouteTags $resolvedTags = null, ?RouteLifetime $resolvedLifetime = null)
     {
         $routeValues = $this->convertObjectsToHashes($resolveContext->getRouteValues());
         if ($routeValues === null) {
diff --git a/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php b/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php
index 5eb57b2a94..b50c702058 100644
--- a/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php
+++ b/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php
@@ -289,7 +289,7 @@ public function reset()
      * @throws Exception\MissingActionNameException if $actionName parameter is empty
      * @throws \Neos\Flow\Http\Exception
      */
-    public function uriFor(string $actionName, array $controllerArguments = [], string $controllerName = null, string $packageKey = null, string $subPackageKey = null)
+    public function uriFor(string $actionName, array $controllerArguments = [], ?string $controllerName = null, ?string $packageKey = null, ?string $subPackageKey = null)
     {
         if (empty($actionName)) {
             throw new Exception\MissingActionNameException('The URI Builder could not build a URI linking to an action controller because no action name was specified. Please check the stack trace to see which code or template was requesting the link and check the arguments passed to the URI Builder.', 1354629891);
diff --git a/Neos.Flow/Classes/Package/PackageFactory.php b/Neos.Flow/Classes/Package/PackageFactory.php
index 8a3725c352..75b4e176f5 100644
--- a/Neos.Flow/Classes/Package/PackageFactory.php
+++ b/Neos.Flow/Classes/Package/PackageFactory.php
@@ -32,7 +32,7 @@ class PackageFactory
      * @return PackageInterface|PackageKeyAwareInterface
      * @throws Exception\CorruptPackageException
      */
-    public function create($packagesBasePath, $packagePath, $packageKey, $composerName, array $autoloadConfiguration = [], array $packageClassInformation = null)
+    public function create($packagesBasePath, $packagePath, $packageKey, $composerName, array $autoloadConfiguration = [], ?array $packageClassInformation = null)
     {
         $absolutePackagePath = Files::concatenatePaths([$packagesBasePath, $packagePath]) . '/';
 
diff --git a/Neos.Flow/Classes/Package/PackageManager.php b/Neos.Flow/Classes/Package/PackageManager.php
index f724e10179..e59f351efc 100644
--- a/Neos.Flow/Classes/Package/PackageManager.php
+++ b/Neos.Flow/Classes/Package/PackageManager.php
@@ -881,7 +881,7 @@ protected function getPackageKeyFromManifest(array $manifest, $packagePath): str
      * @param string $autoloadNamespace
      * @return string
      */
-    protected function derivePackageKey(string $composerName, string $packageType = null, string $packagePath = '', string $autoloadNamespace = null): string
+    protected function derivePackageKey(string $composerName, ?string $packageType = null, string $packagePath = '', ?string $autoloadNamespace = null): string
     {
         $packageKey = '';
 
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php b/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php
index b4b6d09cf4..46bdd4ae3c 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php
@@ -69,7 +69,7 @@ class ArrayTypeConverter extends AbstractTypeConverter
      * @throws TypeConverterException thrown in case a developer error occurred
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $result = [];
         $convertElements = $configuration->getConfigurationValue(ArrayTypeConverter::class, self::CONFIGURATION_CONVERT_ELEMENTS);
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Logging/SqlLogger.php b/Neos.Flow/Classes/Persistence/Doctrine/Logging/SqlLogger.php
index 0878b08a30..df97b36e69 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Logging/SqlLogger.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Logging/SqlLogger.php
@@ -35,7 +35,7 @@ class SqlLogger implements \Doctrine\DBAL\Logging\SQLLogger
      * @param array $types The SQL parameter types.
      * @return void
      */
-    public function startQuery($sql, array $params = null, array $types = null)
+    public function startQuery($sql, ?array $params = null, ?array $types = null)
     {
         if ($this->logger instanceof DependencyProxy) {
             $this->logger->_activateDependency();
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php b/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php
index 7d4afb2c89..c52f1dbbe5 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php
@@ -201,7 +201,7 @@ public function getIdentifierByObject($object)
      * @throws ORMException
      * @api
      */
-    public function getObjectByIdentifier($identifier, string $objectType = null, bool $useLazyLoading = false)
+    public function getObjectByIdentifier($identifier, ?string $objectType = null, bool $useLazyLoading = false)
     {
         if ($objectType === null) {
             throw new \RuntimeException('Using only the identifier is not supported by Doctrine 2. Give classname as well or use repository to query identifier.', 1296646103);
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Repository.php b/Neos.Flow/Classes/Persistence/Doctrine/Repository.php
index f940d5840d..0739714ba6 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Repository.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Repository.php
@@ -64,7 +64,7 @@ abstract class Repository extends EntityRepository implements RepositoryInterfac
      * @param EntityManagerInterface $entityManager The EntityManager to use.
      * @param ClassMetadata|null $classMetadata The class descriptor.
      */
-    public function __construct(EntityManagerInterface $entityManager, ClassMetadata $classMetadata = null)
+    public function __construct(EntityManagerInterface $entityManager, ?ClassMetadata $classMetadata = null)
     {
         if ($classMetadata === null) {
             if (defined('static::ENTITY_CLASSNAME') === false) {
@@ -162,7 +162,7 @@ public function findAllIterator(): IterableResult
      * @param callable|null $callback
      * @return \Generator
      */
-    public function iterate(IterableResult $iterator, callable $callback = null): ?\Generator
+    public function iterate(IterableResult $iterator, ?callable $callback = null): ?\Generator
     {
         $iteration = 0;
         foreach ($iterator as $object) {
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Service.php b/Neos.Flow/Classes/Persistence/Doctrine/Service.php
index c4a7649106..d1a2598656 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Service.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Service.php
@@ -196,7 +196,7 @@ public function getEntityStatus(): array
      * @param int|null $maxResult
      * @return mixed
      */
-    public function runDql(string $dql, int $hydrationMode = \Doctrine\ORM\Query::HYDRATE_OBJECT, int $firstResult = null, int $maxResult = null)
+    public function runDql(string $dql, int $hydrationMode = \Doctrine\ORM\Query::HYDRATE_OBJECT, ?int $firstResult = null, ?int $maxResult = null)
     {
         $query = $this->entityManager->createQuery($dql);
         if ($firstResult !== null) {
@@ -306,7 +306,7 @@ private function getSortedVersions(AvailableMigrationsList $availableMigrations,
      * @return string
      * @throws DBALException
      */
-    public function executeMigrations(string $version = 'latest', string $outputPathAndFilename = null, $dryRun = false, $quiet = false): string
+    public function executeMigrations(string $version = 'latest', ?string $outputPathAndFilename = null, $dryRun = false, $quiet = false): string
     {
         $this->initializeMetadataStorage();
 
@@ -413,7 +413,7 @@ private function exitMessageForAlias(string $versionAlias): string
      * @return string
      * @throws DBALException
      */
-    public function executeMigration(string $version, string $direction = 'up', string $outputPathAndFilename = null, bool $dryRun = false): string
+    public function executeMigration(string $version, string $direction = 'up', ?string $outputPathAndFilename = null, bool $dryRun = false): string
     {
         $this->initializeMetadataStorage();
 
@@ -604,7 +604,7 @@ public function getMigrationStatus(): array
      * @return array Path to the new file
      * @throws DBALException
      */
-    public function generateMigration(bool $diffAgainstCurrent = true, string $filterExpression = null): array
+    public function generateMigration(bool $diffAgainstCurrent = true, ?string $filterExpression = null): array
     {
         $fqcn = $this->getDependencyFactory()->getClassNameGenerator()->generateClassName(self::DOCTRINE_MIGRATIONSNAMESPACE);
 
diff --git a/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php b/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php
index d62ffc1959..33004b0c44 100644
--- a/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php
+++ b/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php
@@ -99,7 +99,7 @@ public function getIdentifierByObject($object);
      * @return object|null The object for the identifier if it is known, or NULL
      * @api
      */
-    public function getObjectByIdentifier($identifier, string $objectType = null, bool $useLazyLoading = false);
+    public function getObjectByIdentifier($identifier, ?string $objectType = null, bool $useLazyLoading = false);
 
     /**
      * Converts the given object into an array containing the identity of the domain object.
diff --git a/Neos.Flow/Classes/Property/PropertyMapper.php b/Neos.Flow/Classes/Property/PropertyMapper.php
index 5aaea7117c..8344fc0d59 100644
--- a/Neos.Flow/Classes/Property/PropertyMapper.php
+++ b/Neos.Flow/Classes/Property/PropertyMapper.php
@@ -108,7 +108,7 @@ public static function getTypeConverterImplementationClassNames($objectManager)
      * @throws SecurityException
      * @api
      */
-    public function convert($source, $targetType, PropertyMappingConfigurationInterface $configuration = null)
+    public function convert($source, $targetType, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             $configuration = $this->buildPropertyMappingConfiguration();
diff --git a/Neos.Flow/Classes/Property/TypeConverter/AbstractTypeConverter.php b/Neos.Flow/Classes/Property/TypeConverter/AbstractTypeConverter.php
index e008c64d79..b9ddd83d08 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/AbstractTypeConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/AbstractTypeConverter.php
@@ -86,7 +86,7 @@ public function getSupportedTargetType()
      * @return string
      * @api
      */
-    public function getTargetTypeForSource($source, $originalTargetType, PropertyMappingConfigurationInterface $configuration = null)
+    public function getTargetTypeForSource($source, $originalTargetType, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return $originalTargetType;
     }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php
index 4dd6e27f10..ca088c34cb 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php
@@ -120,7 +120,7 @@ class ArrayConverter extends AbstractTypeConverter
      * @throws TypeConverterException
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if (is_array($source)) {
             return $source;
@@ -184,7 +184,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getStringDelimiter(PropertyMappingConfigurationInterface $configuration = null)
+    protected function getStringDelimiter(?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return self::DEFAULT_STRING_DELIMITER;
@@ -205,7 +205,7 @@ protected function getStringDelimiter(PropertyMappingConfigurationInterface $con
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getStringFormat(PropertyMappingConfigurationInterface $configuration = null)
+    protected function getStringFormat(?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return self::DEFAULT_STRING_FORMAT;
@@ -226,7 +226,7 @@ protected function getStringFormat(PropertyMappingConfigurationInterface $config
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getResourceExportType(PropertyMappingConfigurationInterface $configuration = null)
+    protected function getResourceExportType(?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return self::DEFAULT_RESOURCE_EXPORT_TYPE;
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php
index d12caf3d75..0c5d63e1d6 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php
@@ -95,7 +95,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      * @return mixed|Error the target type, or an error object if a user-error occurred
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $properties = ObjectAccess::getGettableProperties($source);
         if ($source instanceof DoctrineProxy) {
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php
index e792f7cf03..ea519af032 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php
@@ -51,7 +51,7 @@ class ArrayObjectConverter extends AbstractTypeConverter
      * @throws InvalidSourceException
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null): array
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null): array
     {
         if (!($source instanceof \ArrayObject)) {
             throw new InvalidSourceException('Source was not an instance of ArrayObject.', 1648456200);
diff --git a/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php b/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php
index 2dceaac4ad..460f1b3541 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php
@@ -51,7 +51,7 @@ class BooleanConverter extends AbstractTypeConverter
      * @return boolean
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if (is_bool($source)) {
             return $source;
diff --git a/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php b/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php
index 7d18e3e35c..91755c7d9a 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php
@@ -54,7 +54,7 @@ class CollectionConverter extends AbstractTypeConverter
      * @return ArrayCollection
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return new ArrayCollection($convertedChildProperties);
     }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php b/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php
index 55dbc442e6..c523ffa246 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php
@@ -121,7 +121,7 @@ public function canConvertFrom($source, $targetType)
      * @throws InvalidPropertyMappingConfigurationException
      * @throws TypeConverterException
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $dateFormat = $this->getDefaultDateFormat($configuration);
         $isFormatSpecified = false;
@@ -197,7 +197,7 @@ protected function isDatePartKeysProvided(array $source)
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getDefaultDateFormat(PropertyMappingConfigurationInterface $configuration = null)
+    protected function getDefaultDateFormat(?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return self::DEFAULT_DATE_FORMAT;
diff --git a/Neos.Flow/Classes/Property/TypeConverter/DenormalizingObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/DenormalizingObjectConverter.php
index 5b5c5131f2..628947f720 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/DenormalizingObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/DenormalizingObjectConverter.php
@@ -40,7 +40,7 @@ public function getSupportedTargetType()
      * @return string
      * @api
      */
-    public function getTargetTypeForSource($source, $originalTargetType, PropertyMappingConfigurationInterface $configuration = null)
+    public function getTargetTypeForSource($source, $originalTargetType, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return $originalTargetType;
     }
@@ -142,7 +142,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      * @throws TypeConverterException thrown in case a developer error occurred
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return self::convertFromSource($source, $targetType);
     }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php b/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php
index ea7f0463e4..2cabd6bca5 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php
@@ -130,7 +130,7 @@ class FloatConverter extends AbstractTypeConverter
      * @throws InvalidPropertyMappingConfigurationException
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($source === null || $source === '') {
             return null;
diff --git a/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php b/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php
index 78af1b6c69..591fa47cef 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php
@@ -52,7 +52,7 @@ class IntegerConverter extends AbstractTypeConverter
      * @return integer|Error
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($source instanceof \DateTimeInterface) {
             return $source->format('U');
diff --git a/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php b/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php
index 39746cbbc2..0959a3540a 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php
@@ -53,7 +53,7 @@ class MediaTypeConverter extends AbstractTypeConverter implements MediaTypeConve
      * @return array|string|integer Note that this TypeConverter may return a non-array in case of JSON media type, even though he declares to only convert to array
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $mediaType = null;
         if ($configuration !== null) {
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php
index b240e8ba86..0c350a3cfa 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php
@@ -180,7 +180,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      * @throws InvalidDataTypeException
      * @throws InvalidPropertyMappingConfigurationException
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $object = $this->buildObject($convertedChildProperties, $targetType);
         foreach ($convertedChildProperties as $propertyName => $propertyValue) {
@@ -210,7 +210,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      * @throws InvalidPropertyMappingConfigurationException
      * @throws \InvalidArgumentException
      */
-    public function getTargetTypeForSource($source, $originalTargetType, PropertyMappingConfigurationInterface $configuration = null)
+    public function getTargetTypeForSource($source, $originalTargetType, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $targetType = $originalTargetType;
 
diff --git a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php
index 53ec73f776..14d0f98832 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php
@@ -159,7 +159,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      * @return object|TargetNotFoundError the converted entity/value object or an instance of TargetNotFoundError if the object could not be resolved
      * @throws \InvalidArgumentException|InvalidTargetException
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         /** @var class-string $targetType */
         if (is_array($source)) {
@@ -230,7 +230,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      * @return object|TargetNotFoundError
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function handleArrayData(array $source, $targetType, array &$convertedChildProperties, PropertyMappingConfigurationInterface $configuration = null)
+    protected function handleArrayData(array $source, $targetType, array &$convertedChildProperties, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if (!isset($source['__identity'])) {
             if ($this->reflectionService->isClassAnnotatedWith($targetType, ValueObject::class) === true) {
diff --git a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php
index f554bf54ee..27bf3b2758 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php
@@ -56,7 +56,7 @@ class PersistentObjectSerializer extends AbstractTypeConverter
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return mixed The identifier for the object if it is known, or NULL
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return $this->persistenceManager->getIdentifierByObject($source);
     }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php
index 4a3dbc7bf2..a01cd9da59 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php
@@ -83,7 +83,7 @@ public function canConvertFrom($source, $targetType)
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return object
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return new $targetType($source);
     }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php b/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php
index 1230d36107..0ffe2e9b94 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php
@@ -74,7 +74,7 @@ public function canConvertFrom($source, $targetType)
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return object the target type
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return $this->sessionManager->getSession($source);
     }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php b/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php
index bee883704d..dce5764954 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php
@@ -100,7 +100,7 @@ class StringConverter extends AbstractTypeConverter
      * @throws InvalidPropertyMappingConfigurationException
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($source instanceof \DateTimeInterface) {
             $dateFormat = $this->getDateFormat($configuration);
@@ -131,7 +131,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getDateFormat(PropertyMappingConfigurationInterface $configuration = null)
+    protected function getDateFormat(?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return self::DEFAULT_DATE_FORMAT;
@@ -156,7 +156,7 @@ protected function getDateFormat(PropertyMappingConfigurationInterface $configur
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getCsvDelimiter(PropertyMappingConfigurationInterface $configuration = null)
+    protected function getCsvDelimiter(?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return self::DEFAULT_CSV_DELIMITER;
@@ -181,7 +181,7 @@ protected function getCsvDelimiter(PropertyMappingConfigurationInterface $config
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getArrayFormat(PropertyMappingConfigurationInterface $configuration = null)
+    protected function getArrayFormat(?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return self::DEFAULT_ARRAY_FORMAT;
diff --git a/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php b/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php
index a77a2c7e63..f183ca93cf 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php
@@ -63,7 +63,7 @@ public function canConvertFrom($source, $targetType)
      * @return array
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return $convertedChildProperties;
     }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php b/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php
index 7c27da3e61..f8556886df 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php
@@ -50,7 +50,7 @@ class UriTypeConverter extends AbstractTypeConverter
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return Uri|Error if the input format is not supported or could not be converted for other reasons
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         try {
             return new Uri($source);
diff --git a/Neos.Flow/Classes/Property/TypeConverterInterface.php b/Neos.Flow/Classes/Property/TypeConverterInterface.php
index ca277632fa..3a5df44077 100644
--- a/Neos.Flow/Classes/Property/TypeConverterInterface.php
+++ b/Neos.Flow/Classes/Property/TypeConverterInterface.php
@@ -49,7 +49,7 @@ public function getSupportedTargetType();
      * @return string
      * @api
      */
-    public function getTargetTypeForSource($source, $originalTargetType, PropertyMappingConfigurationInterface $configuration = null);
+    public function getTargetTypeForSource($source, $originalTargetType, ?PropertyMappingConfigurationInterface $configuration = null);
 
     /**
      * Return the priority of this TypeConverter. TypeConverters with a high priority are chosen before low priority.
@@ -110,5 +110,5 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      * @throws Exception\TypeConverterException thrown in case a developer error occurred
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null);
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null);
 }
diff --git a/Neos.Flow/Classes/ResourceManagement/Collection.php b/Neos.Flow/Classes/ResourceManagement/Collection.php
index 281e9ba1fe..46199e4e26 100644
--- a/Neos.Flow/Classes/ResourceManagement/Collection.php
+++ b/Neos.Flow/Classes/ResourceManagement/Collection.php
@@ -155,7 +155,7 @@ public function publish()
      * @param callable $callback Function called after each object
      * @return \Generator<StorageObject>
      */
-    public function getObjects(callable $callback = null)
+    public function getObjects(?callable $callback = null)
     {
         if ($this->storage instanceof PackageStorage && $this->pathPatterns !== []) {
             foreach ($this->pathPatterns as $pathPattern) {
diff --git a/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php b/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php
index ae8d5a44aa..ffba74d24a 100644
--- a/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php
+++ b/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php
@@ -107,7 +107,7 @@ public function hasMessages(): bool
      * @return void
      * @api
      */
-    public function flush(callable $callback = null): void
+    public function flush(?callable $callback = null): void
     {
         foreach ($this->messages as $message) {
             /** @var Message $message */
diff --git a/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php b/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php
index 85ea1d0eaa..66af5f8bc1 100644
--- a/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php
+++ b/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php
@@ -144,7 +144,7 @@ public function findByIdentifier($identifier)
      * @param callable $callback
      * @return \Generator
      */
-    public function iterate(IterableResult $iterator, callable $callback = null)
+    public function iterate(IterableResult $iterator, ?callable $callback = null)
     {
         $iteration = 0;
         foreach ($iterator as $object) {
diff --git a/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php b/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php
index ed1819b910..fc81836e5b 100644
--- a/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php
+++ b/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php
@@ -153,7 +153,7 @@ public function injectLogger(LoggerInterface $logger)
      * @throws Exception\InvalidResourceDataException
      * @throws InvalidPropertyMappingConfigurationException
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if (empty($source)) {
             return null;
@@ -181,7 +181,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return PersistentResource|null|FlowError
      */
-    protected function handleFileUploads(array $source, PropertyMappingConfigurationInterface $configuration = null)
+    protected function handleFileUploads(array $source, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if (!isset($source['error']) || $source['error'] === \UPLOAD_ERR_NO_FILE) {
             if (isset($source['originallySubmittedResource']) && isset($source['originallySubmittedResource']['__identity'])) {
@@ -226,7 +226,7 @@ protected function handleFileUploads(array $source, PropertyMappingConfiguration
      * @throws Exception\InvalidResourceDataException
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function handleHashAndData(array $source, PropertyMappingConfigurationInterface $configuration = null)
+    protected function handleHashAndData(array $source, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $hash = null;
         $resource = null;
@@ -278,7 +278,7 @@ protected function handleHashAndData(array $source, PropertyMappingConfiguration
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return PersistentResource|null|FlowError
      */
-    protected function handleUploadedFile(UploadedFileInterface $source, PropertyMappingConfigurationInterface $configuration = null)
+    protected function handleUploadedFile(UploadedFileInterface $source, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($source instanceof FlowUploadedFile && $source->getError() === UPLOAD_ERR_NO_FILE && $source->getOriginallySubmittedResource() !== null) {
             $identifier = is_array($source->getOriginallySubmittedResource()) ? $source->getOriginallySubmittedResource()['__identity'] : $source->getOriginallySubmittedResource();
@@ -329,7 +329,7 @@ protected function handleUploadedFile(UploadedFileInterface $source, PropertyMap
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
      */
-    protected function getCollectionName($source, PropertyMappingConfigurationInterface $configuration = null)
+    protected function getCollectionName($source, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             return ResourceManager::DEFAULT_PERSISTENT_COLLECTION_NAME;
diff --git a/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php b/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php
index 45672f1631..69d9739bec 100644
--- a/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php
+++ b/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php
@@ -133,7 +133,7 @@ public function getStreamByResourcePath($relativePath)
      * @param callable|null $callback Function called after each iteration
      * @return \Generator<StorageObject>
      */
-    public function getObjects(callable $callback = null)
+    public function getObjects(?callable $callback = null)
     {
         foreach ($this->resourceManager->getCollectionsByStorage($this) as $collection) {
             yield from $this->getObjectsByCollection($collection, $callback);
@@ -147,7 +147,7 @@ public function getObjects(callable $callback = null)
      * @param callable|null $callback Function called after each iteration
      * @return \Generator<StorageObject>
      */
-    public function getObjectsByCollection(CollectionInterface $collection, callable $callback = null)
+    public function getObjectsByCollection(CollectionInterface $collection, ?callable $callback = null)
     {
         $iterator = $this->resourceRepository->findByCollectionNameIterator($collection->getName());
         $iteration = 0;
diff --git a/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php b/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php
index 724eb4d2bd..97f8e1277c 100644
--- a/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php
+++ b/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php
@@ -45,7 +45,7 @@ public function initializeObject()
      * @param callable $callback Function called after each iteration
      * @return \Generator<StorageObject>
      */
-    public function getObjects(callable $callback = null)
+    public function getObjects(?callable $callback = null)
     {
         return $this->getObjectsByPathPattern('*');
     }
@@ -57,7 +57,7 @@ public function getObjects(callable $callback = null)
      * @param callable $callback Function called after each object
      * @return \Generator<StorageObject>
      */
-    public function getObjectsByPathPattern($pattern, callable $callback = null)
+    public function getObjectsByPathPattern($pattern, ?callable $callback = null)
     {
         $directories = [];
 
diff --git a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php
index d611914a3d..751c2c1827 100644
--- a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php
+++ b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php
@@ -35,7 +35,7 @@ class FileSystemSymlinkTarget extends FileSystemTarget
      * @param callable $callback Function called after each resource publishing
      * @return void
      */
-    public function publishCollection(CollectionInterface $collection, callable $callback = null)
+    public function publishCollection(CollectionInterface $collection, ?callable $callback = null)
     {
         $storage = $collection->getStorage();
         if ($storage instanceof PackageStorage) {
diff --git a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php
index af71858c29..8e2b101bfe 100644
--- a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php
+++ b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php
@@ -193,7 +193,7 @@ protected function checkAndRemovePackageSymlinks(StorageInterface $storage)
      * @param callable $callback Function called after each resource publishing
      * @return void
      */
-    public function publishCollection(CollectionInterface $collection, callable $callback = null)
+    public function publishCollection(CollectionInterface $collection, ?callable $callback = null)
     {
         $storage = $collection->getStorage();
         $this->checkAndRemovePackageSymlinks($storage);
diff --git a/Neos.Flow/Classes/Security/Account.php b/Neos.Flow/Classes/Security/Account.php
index dca697973b..c0dd309da0 100644
--- a/Neos.Flow/Classes/Security/Account.php
+++ b/Neos.Flow/Classes/Security/Account.php
@@ -314,7 +314,7 @@ public function getExpirationDate()
      * @return void
      * @api
      */
-    public function setExpirationDate(\DateTime $expirationDate = null)
+    public function setExpirationDate(?\DateTime $expirationDate = null)
     {
         $this->expirationDate = $expirationDate;
     }
diff --git a/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php b/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php
index 6861e19ce0..5c77e901a8 100644
--- a/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php
+++ b/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php
@@ -118,7 +118,7 @@ public function logoutAction()
      * @param AuthenticationRequiredException $exception The exception thrown while the authentication process
      * @return void
      */
-    protected function onAuthenticationFailure(AuthenticationRequiredException $exception = null)
+    protected function onAuthenticationFailure(?AuthenticationRequiredException $exception = null)
     {
         $this->controllerContext->getFlashMessageContainer()->addMessage(new Error('Authentication failed!', ($exception === null ? 1347016771 : $exception->getCode())));
     }
@@ -137,7 +137,7 @@ protected function onAuthenticationFailure(AuthenticationRequiredException $exce
      * @param ActionRequest $originalRequest The request that was intercepted by the security framework, NULL if there was none
      * @return string
      */
-    abstract protected function onAuthenticationSuccess(ActionRequest $originalRequest = null);
+    abstract protected function onAuthenticationSuccess(?ActionRequest $originalRequest = null);
 
 
     /**
diff --git a/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php b/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php
index b8bc6e5ed3..42900ce9f6 100644
--- a/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php
+++ b/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php
@@ -68,7 +68,7 @@ abstract class AbstractToken implements TokenInterface
      *
      * @param array|null $options
      */
-    public function __construct(array $options = null)
+    public function __construct(?array $options = null)
     {
         $this->options = $options ?? [];
     }
@@ -189,7 +189,7 @@ public function getAccount()
      * @param Account $account An account object
      * @return void
      */
-    public function setAccount(Account $account = null)
+    public function setAccount(?Account $account = null)
     {
         $this->account = $account;
     }
diff --git a/Neos.Flow/Classes/Security/Authentication/TokenInterface.php b/Neos.Flow/Classes/Security/Authentication/TokenInterface.php
index e3a6246454..13b6eb868c 100644
--- a/Neos.Flow/Classes/Security/Authentication/TokenInterface.php
+++ b/Neos.Flow/Classes/Security/Authentication/TokenInterface.php
@@ -149,7 +149,7 @@ public function getAccount();
      * @param Account $account An account object
      * @return void
      */
-    public function setAccount(Account $account = null);
+    public function setAccount(?Account $account = null);
 
     /**
      * Returns a string representation of the token for logging purposes.
diff --git a/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php b/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php
index 2b02d59faf..6efd9bb355 100644
--- a/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php
+++ b/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php
@@ -154,7 +154,7 @@ public function isPrivilegeTargetGrantedForRoles(array $roles, $privilegeTargetI
      * @param PrivilegeInterface|null $privilege
      * @return PrivilegePermissionResult
      */
-    protected function applyPrivilegeToResult(PrivilegePermissionResult $result, PrivilegeInterface $privilege = null): PrivilegePermissionResult
+    protected function applyPrivilegeToResult(PrivilegePermissionResult $result, ?PrivilegeInterface $privilege = null): PrivilegePermissionResult
     {
         return $result->withPrivilege($privilege);
     }
diff --git a/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php b/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php
index 4ed3d1f424..92eabf6397 100644
--- a/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php
+++ b/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php
@@ -47,7 +47,7 @@ public function __construct(int $denies = 0, int $grants = 0, int $abstains = 0)
      * @param PrivilegeInterface $privilege
      * @return PrivilegePermissionResult
      */
-    public function withPrivilege(PrivilegeInterface $privilege = null): PrivilegePermissionResult
+    public function withPrivilege(?PrivilegeInterface $privilege = null): PrivilegePermissionResult
     {
         $newResult = clone $this;
         if ($privilege === null) {
diff --git a/Neos.Flow/Classes/Security/Context.php b/Neos.Flow/Classes/Security/Context.php
index 034c0234f4..3e7ac534cd 100644
--- a/Neos.Flow/Classes/Security/Context.php
+++ b/Neos.Flow/Classes/Security/Context.php
@@ -576,7 +576,7 @@ public function isCsrfProtectionTokenValid($csrfToken)
      * @return void
      * @Flow\Session(autoStart=true)
      */
-    public function setInterceptedRequest(ActionRequest $interceptedRequest = null)
+    public function setInterceptedRequest(?ActionRequest $interceptedRequest = null)
     {
         if ($this->initialized === false) {
             $this->initialize();
diff --git a/Neos.Flow/Classes/Security/DummyContext.php b/Neos.Flow/Classes/Security/DummyContext.php
index ce31b34a04..06f6a638de 100644
--- a/Neos.Flow/Classes/Security/DummyContext.php
+++ b/Neos.Flow/Classes/Security/DummyContext.php
@@ -222,7 +222,7 @@ public function isCsrfProtectionTokenValid($csrfToken)
      * @return void
      * @Flow\Session(autoStart=true)
      */
-    public function setInterceptedRequest(ActionRequest $interceptedRequest = null)
+    public function setInterceptedRequest(?ActionRequest $interceptedRequest = null)
     {
         $this->interceptedRequest = $interceptedRequest;
     }
diff --git a/Neos.Flow/Classes/Security/Policy/RoleConverter.php b/Neos.Flow/Classes/Security/Policy/RoleConverter.php
index a807e0341e..3a3c04ec44 100644
--- a/Neos.Flow/Classes/Security/Policy/RoleConverter.php
+++ b/Neos.Flow/Classes/Security/Policy/RoleConverter.php
@@ -56,7 +56,7 @@ class RoleConverter extends AbstractTypeConverter
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return object the target type
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         try {
             $role = $this->policyService->getRole($source);
diff --git a/Neos.Flow/Classes/Security/SessionDataContainer.php b/Neos.Flow/Classes/Security/SessionDataContainer.php
index f0f4a3c183..d35fb8e870 100644
--- a/Neos.Flow/Classes/Security/SessionDataContainer.php
+++ b/Neos.Flow/Classes/Security/SessionDataContainer.php
@@ -92,7 +92,7 @@ public function getInterceptedRequest(): ?ActionRequest
      *
      * @param ActionRequest $interceptedRequest
      */
-    public function setInterceptedRequest(ActionRequest $interceptedRequest = null): void
+    public function setInterceptedRequest(?ActionRequest $interceptedRequest = null): void
     {
         $this->interceptedRequest = $interceptedRequest;
     }
diff --git a/Neos.Flow/Classes/Validation/ValidatorResolver.php b/Neos.Flow/Classes/Validation/ValidatorResolver.php
index 3cd11c7b55..54ff349e36 100644
--- a/Neos.Flow/Classes/Validation/ValidatorResolver.php
+++ b/Neos.Flow/Classes/Validation/ValidatorResolver.php
@@ -160,7 +160,7 @@ public function getBaseValidatorConjunction($targetClassName, array $validationG
      * @throws Exception\InvalidTypeHintException
      * @throws Exception\InvalidValidationOptionsException
      */
-    public function buildMethodArgumentsValidatorConjunctions($className, $methodName, array $methodParameters = null, array $methodValidateAnnotations = null)
+    public function buildMethodArgumentsValidatorConjunctions($className, $methodName, ?array $methodParameters = null, ?array $methodValidateAnnotations = null)
     {
         $validatorConjunctions = [];
 
diff --git a/Neos.Flow/Scripts/Migrations/Manager.php b/Neos.Flow/Scripts/Migrations/Manager.php
index fde91d0e59..c26ca8875f 100644
--- a/Neos.Flow/Scripts/Migrations/Manager.php
+++ b/Neos.Flow/Scripts/Migrations/Manager.php
@@ -331,7 +331,7 @@ public function on($eventIdentifier, \Closure $callback)
      * @param string $eventIdentifier one of the EVENT_* constants
      * @param array $eventData optional arguments to be passed to the handler closure
      */
-    protected function triggerEvent($eventIdentifier, array $eventData = null)
+    protected function triggerEvent($eventIdentifier, ?array $eventData = null)
     {
         if (!isset($this->eventCallbacks[$eventIdentifier])) {
             return;
diff --git a/Neos.Flow/Tests/Functional/Aop/Fixtures/TargetClass01.php b/Neos.Flow/Tests/Functional/Aop/Fixtures/TargetClass01.php
index e56bd6c5ca..2bb791fd67 100644
--- a/Neos.Flow/Tests/Functional/Aop/Fixtures/TargetClass01.php
+++ b/Neos.Flow/Tests/Functional/Aop/Fixtures/TargetClass01.php
@@ -132,7 +132,7 @@ public function getCurrentName()
      * @param Fixtures\Name $name
      * @return void
      */
-    public function setCurrentName(Fixtures\Name $name = null)
+    public function setCurrentName(?Fixtures\Name $name = null)
     {
         $this->currentName = $name;
     }
diff --git a/Neos.Flow/Tests/Functional/Command/PyStringNodeConverter.php b/Neos.Flow/Tests/Functional/Command/PyStringNodeConverter.php
index 2d0e1702a5..44f1a63cb1 100644
--- a/Neos.Flow/Tests/Functional/Command/PyStringNodeConverter.php
+++ b/Neos.Flow/Tests/Functional/Command/PyStringNodeConverter.php
@@ -45,7 +45,7 @@ class PyStringNodeConverter extends AbstractTypeConverter
      * @return TableNode
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return new TableNode(json_decode($source, true));
     }
diff --git a/Neos.Flow/Tests/Functional/Command/TableNodeConverter.php b/Neos.Flow/Tests/Functional/Command/TableNodeConverter.php
index 3a18b9249f..053aa55420 100644
--- a/Neos.Flow/Tests/Functional/Command/TableNodeConverter.php
+++ b/Neos.Flow/Tests/Functional/Command/TableNodeConverter.php
@@ -45,7 +45,7 @@ class TableNodeConverter extends AbstractTypeConverter
      * @return TableNode
      * @api
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return new TableNode(json_decode($source, true));
     }
diff --git a/Neos.Flow/Tests/Functional/Mvc/Fixtures/Controller/ActionControllerTestBController.php b/Neos.Flow/Tests/Functional/Mvc/Fixtures/Controller/ActionControllerTestBController.php
index 9e754a0cf9..5cb752b102 100644
--- a/Neos.Flow/Tests/Functional/Mvc/Fixtures/Controller/ActionControllerTestBController.php
+++ b/Neos.Flow/Tests/Functional/Mvc/Fixtures/Controller/ActionControllerTestBController.php
@@ -57,7 +57,7 @@ public function requiredObjectAction(TestObjectArgument $argument)
      * @param TestObjectArgument $argument
      * @return string
      */
-    public function optionalObjectAction(TestObjectArgument $argument = null)
+    public function optionalObjectAction(?TestObjectArgument $argument = null)
     {
         if ($argument === null) {
             return 'null';
@@ -69,7 +69,7 @@ public function optionalObjectAction(TestObjectArgument $argument = null)
      * @param TestObjectArgument|null $argument
      * @return string
      */
-    public function optionalAnnotatedObjectAction(TestObjectArgument $argument = null)
+    public function optionalAnnotatedObjectAction(?TestObjectArgument $argument = null)
     {
         if ($argument === null) {
             return 'null';
@@ -265,7 +265,7 @@ public function requiredDateAction(\DateTime $argument)
      * @param \DateTime $argument
      * @return string
      */
-    public function optionalDateAction(\DateTime $argument = null)
+    public function optionalDateAction(?\DateTime $argument = null)
     {
         if ($argument === null) {
             return 'null';
diff --git a/Neos.Flow/Tests/Functional/Mvc/RoutingTest.php b/Neos.Flow/Tests/Functional/Mvc/RoutingTest.php
index 726aeddce6..52a3406d51 100644
--- a/Neos.Flow/Tests/Functional/Mvc/RoutingTest.php
+++ b/Neos.Flow/Tests/Functional/Mvc/RoutingTest.php
@@ -66,7 +66,7 @@ protected function setUp(): void
      * @param array $matchResults
      * @return ActionRequest
      */
-    protected function createActionRequest(ServerRequestInterface $httpRequest, array $matchResults = null): ActionRequest
+    protected function createActionRequest(ServerRequestInterface $httpRequest, ?array $matchResults = null): ActionRequest
     {
         $actionRequest = ActionRequest::fromHttpRequest($httpRequest);
         if ($matchResults !== null) {
@@ -203,7 +203,7 @@ public function routeTestsDataProvider(): array
      * @test
      * @dataProvider routeTestsDataProvider
      */
-    public function routeTests($requestUri, $expectedMatchingRouteName, $expectedControllerObjectName = null, array $expectedArguments = null)
+    public function routeTests($requestUri, $expectedMatchingRouteName, $expectedControllerObjectName = null, ?array $expectedArguments = null)
     {
         $request = $this->serverRequestFactory->createServerRequest('GET', new Uri($requestUri));
         try {
diff --git a/Neos.Flow/Tests/Functional/Persistence/Fixtures/ExtendedTypesEntity.php b/Neos.Flow/Tests/Functional/Persistence/Fixtures/ExtendedTypesEntity.php
index cf453a73fe..9a17d8b1fc 100644
--- a/Neos.Flow/Tests/Functional/Persistence/Fixtures/ExtendedTypesEntity.php
+++ b/Neos.Flow/Tests/Functional/Persistence/Fixtures/ExtendedTypesEntity.php
@@ -106,7 +106,7 @@ public function getTime()
      * @param \DateTime $date
      * @return $this
      */
-    public function setDate(\DateTime $date = null)
+    public function setDate(?\DateTime $date = null)
     {
         $this->date = $date;
         return $this;
@@ -124,7 +124,7 @@ public function getDate()
      * @param \DateTime $dateTimeTz
      * @return $this
      */
-    public function setDateTimeTz(\DateTime $dateTimeTz = null)
+    public function setDateTimeTz(?\DateTime $dateTimeTz = null)
     {
         $this->dateTimeTz = $dateTimeTz;
         return $this;
@@ -142,7 +142,7 @@ public function getDateTimeTz()
      * @param \DateTime $dateTime
      * @return $this
      */
-    public function setDateTime(\DateTime $dateTime = null)
+    public function setDateTime(?\DateTime $dateTime = null)
     {
         $this->dateTime = $dateTime;
         return $this;
@@ -160,7 +160,7 @@ public function getDateTime()
      * @param \DateTimeImmutable $dateTime
      * @return $this
      */
-    public function setDateTimeImmutable(\DateTimeImmutable $dateTime = null)
+    public function setDateTimeImmutable(?\DateTimeImmutable $dateTime = null)
     {
         $this->dateTimeImmutable = $dateTime;
         return $this;
@@ -178,7 +178,7 @@ public function getDateTimeImmutable()
      * @param \DateTimeInterface $dateTime
      * @return $this
      */
-    public function setDateTimeInterface(\DateTimeInterface $dateTime = null)
+    public function setDateTimeInterface(?\DateTimeInterface $dateTime = null)
     {
         $this->dateTimeInterface = $dateTime;
         return $this;
@@ -196,7 +196,7 @@ public function getDateTimeInterface()
      * @param CommonObject $commonObject
      * @return $this
      */
-    public function setCommonObject(CommonObject $commonObject = null)
+    public function setCommonObject(?CommonObject $commonObject = null)
     {
         $this->commonObject = $commonObject;
         return $this;
@@ -214,7 +214,7 @@ public function getCommonObject()
      * @param array $simpleArray
      * @return $this
      */
-    public function setSimpleArray(array $simpleArray = null)
+    public function setSimpleArray(?array $simpleArray = null)
     {
         $this->simpleArray = $simpleArray;
         return $this;
@@ -232,7 +232,7 @@ public function getSimpleArray()
      * @param array $jsonArray
      * @return $this
      */
-    public function setJsonArray(array $jsonArray = null)
+    public function setJsonArray(?array $jsonArray = null)
     {
         $this->jsonArray = $jsonArray;
         return $this;
diff --git a/Neos.Flow/Tests/Functional/Persistence/Fixtures/Image.php b/Neos.Flow/Tests/Functional/Persistence/Fixtures/Image.php
index f110b69bbf..cd93aa2453 100644
--- a/Neos.Flow/Tests/Functional/Persistence/Fixtures/Image.php
+++ b/Neos.Flow/Tests/Functional/Persistence/Fixtures/Image.php
@@ -61,7 +61,7 @@ public function getRelatedObject()
     /**
      * @param CleanupObject $relatedObject
      */
-    public function setRelatedObject(CleanupObject $relatedObject = null)
+    public function setRelatedObject(?CleanupObject $relatedObject = null)
     {
         $this->relatedObject = $relatedObject;
     }
diff --git a/Neos.Flow/Tests/Functional/Property/Fixtures/BoolToIntConverter.php b/Neos.Flow/Tests/Functional/Property/Fixtures/BoolToIntConverter.php
index 853800dc94..c3bbd9d4ee 100644
--- a/Neos.Flow/Tests/Functional/Property/Fixtures/BoolToIntConverter.php
+++ b/Neos.Flow/Tests/Functional/Property/Fixtures/BoolToIntConverter.php
@@ -43,7 +43,7 @@ class BoolToIntConverter extends AbstractTypeConverter
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return bool|Error
      */
-    public function convertFrom($source, $targetType, array $convertedChildProperties = [], PropertyMappingConfigurationInterface $configuration = null)
+    public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         return $source ? 42 : -42;
     }
diff --git a/Neos.Flow/Tests/Functional/Property/PropertyMapperTest.php b/Neos.Flow/Tests/Functional/Property/PropertyMapperTest.php
index f43f45227f..9317348e62 100644
--- a/Neos.Flow/Tests/Functional/Property/PropertyMapperTest.php
+++ b/Neos.Flow/Tests/Functional/Property/PropertyMapperTest.php
@@ -353,7 +353,7 @@ public function mappingToFieldsFromSubclassWorksIfTargetTypeIsOverridden()
      * @test
      * @dataProvider invalidTypeConverterConfigurationsForOverridingTargetTypes
      */
-    public function mappingToFieldsFromSubclassThrowsExceptionIfTypeConverterOptionIsInvalidOrNotSet(PropertyMappingConfigurationInterface $configuration = null)
+    public function mappingToFieldsFromSubclassThrowsExceptionIfTypeConverterOptionIsInvalidOrNotSet(?PropertyMappingConfigurationInterface $configuration = null)
     {
         $this->expectException(Exception::class);
         $source = [
diff --git a/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/AuthenticationController.php b/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/AuthenticationController.php
index 71479e97d8..1d53f422d0 100644
--- a/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/AuthenticationController.php
+++ b/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/AuthenticationController.php
@@ -26,7 +26,7 @@ class AuthenticationController extends AbstractAuthenticationController
      * @param ActionRequest $originalRequest
      * @return string
      */
-    public function onAuthenticationSuccess(ActionRequest $originalRequest = null)
+    public function onAuthenticationSuccess(?ActionRequest $originalRequest = null)
     {
         if ($originalRequest !== null) {
             $this->redirectToRequest($originalRequest);
@@ -38,7 +38,7 @@ public function onAuthenticationSuccess(ActionRequest $originalRequest = null)
      * @param AuthenticationRequiredException $exception
      * @throws FlowException
      */
-    public function onAuthenticationFailure(AuthenticationRequiredException $exception = null)
+    public function onAuthenticationFailure(?AuthenticationRequiredException $exception = null)
     {
         throw new FlowException('Failure Method Exception', 42);
     }
diff --git a/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/HttpBasicTestController.php b/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/HttpBasicTestController.php
index 52bb094c31..f4252f3a94 100644
--- a/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/HttpBasicTestController.php
+++ b/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/HttpBasicTestController.php
@@ -26,7 +26,7 @@ class HttpBasicTestController extends AbstractAuthenticationController
      * @param ActionRequest $originalRequest
      * @return string
      */
-    public function onAuthenticationSuccess(ActionRequest $originalRequest = null)
+    public function onAuthenticationSuccess(?ActionRequest $originalRequest = null)
     {
         if ($originalRequest !== null) {
             $this->redirectToRequest($originalRequest);
@@ -42,7 +42,7 @@ public function onAuthenticationSuccess(ActionRequest $originalRequest = null)
      * @param AuthenticationRequiredException $exception
      * @throws FlowException
      */
-    public function onAuthenticationFailure(AuthenticationRequiredException $exception = null)
+    public function onAuthenticationFailure(?AuthenticationRequiredException $exception = null)
     {
         throw new FlowException('Failure Method Exception', 42);
     }
diff --git a/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/UsernamePasswordTestController.php b/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/UsernamePasswordTestController.php
index 6540f903a4..285dd1d8dd 100644
--- a/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/UsernamePasswordTestController.php
+++ b/Neos.Flow/Tests/Functional/Security/Fixtures/Controller/UsernamePasswordTestController.php
@@ -26,7 +26,7 @@ class UsernamePasswordTestController extends AbstractAuthenticationController
      * @param ActionRequest $originalRequest
      * @return string
      */
-    public function onAuthenticationSuccess(ActionRequest $originalRequest = null)
+    public function onAuthenticationSuccess(?ActionRequest $originalRequest = null)
     {
         if ($originalRequest !== null) {
             $this->redirectToRequest($originalRequest);
@@ -42,7 +42,7 @@ public function onAuthenticationSuccess(ActionRequest $originalRequest = null)
      * @param AuthenticationRequiredException $exception
      * @throws FlowException
      */
-    public function onAuthenticationFailure(AuthenticationRequiredException $exception = null)
+    public function onAuthenticationFailure(?AuthenticationRequiredException $exception = null)
     {
         throw new FlowException('UsernamePasswordTestController failure!', 27);
     }
diff --git a/Neos.Flow/Tests/FunctionalTestCase.php b/Neos.Flow/Tests/FunctionalTestCase.php
index 6af2923449..035c9ba06c 100644
--- a/Neos.Flow/Tests/FunctionalTestCase.php
+++ b/Neos.Flow/Tests/FunctionalTestCase.php
@@ -359,7 +359,7 @@ protected function disableAuthorization()
      * @return Route
      * @api
      */
-    protected function registerRoute($name, $uriPattern, array $defaults, $appendExceedingArguments = false, array $httpMethods = null)
+    protected function registerRoute($name, $uriPattern, array $defaults, $appendExceedingArguments = false, ?array $httpMethods = null)
     {
         $route = new Route();
         $route->setName($name);
diff --git a/Neos.Flow/Tests/Unit/Configuration/ConfigurationManagerTest.php b/Neos.Flow/Tests/Unit/Configuration/ConfigurationManagerTest.php
index 960ff6cfcd..a2bf557c06 100644
--- a/Neos.Flow/Tests/Unit/Configuration/ConfigurationManagerTest.php
+++ b/Neos.Flow/Tests/Unit/Configuration/ConfigurationManagerTest.php
@@ -1784,7 +1784,7 @@ public function loadingConfigurationOfCustomConfigurationTypeCallback($filenameA
      * @param array $methods
      * @return ConfigurationManager|MockObject
      */
-    protected function getAccessibleConfigurationManager(array $methods = [], ApplicationContext $customContext = null)
+    protected function getAccessibleConfigurationManager(array $methods = [], ?ApplicationContext $customContext = null)
     {
         return $this->getAccessibleMock(ConfigurationManager::class, $methods, [$customContext ?? $this->mockContext]);
     }
diff --git a/Neos.Flow/Tests/Unit/Http/Middleware/SecurityEntryPointMiddlewareTest.php b/Neos.Flow/Tests/Unit/Http/Middleware/SecurityEntryPointMiddlewareTest.php
index 6513752ef6..9b8b5c255c 100644
--- a/Neos.Flow/Tests/Unit/Http/Middleware/SecurityEntryPointMiddlewareTest.php
+++ b/Neos.Flow/Tests/Unit/Http/Middleware/SecurityEntryPointMiddlewareTest.php
@@ -357,7 +357,7 @@ public function processMergesArgumentsWithRoutingMatchResultsDataProvider()
      * @test
      * @dataProvider processMergesArgumentsWithRoutingMatchResultsDataProvider()
      */
-    public function processMergesArgumentsWithRoutingMatchResults(array $requestArguments, array $requestBodyArguments, array $routingMatchResults = null, array $expectedArguments)
+    public function processMergesArgumentsWithRoutingMatchResults(array $requestArguments, array $requestBodyArguments, ?array $routingMatchResults = null, array $expectedArguments)
     {
         $this->mockActionRequest->expects(self::once())->method('setArguments')->with($expectedArguments);
         $this->buildMockHttpRequest($requestArguments, $requestBodyArguments);
diff --git a/Neos.Flow/Tests/Unit/Mvc/Routing/Fixtures/MockRoutePartHandler.php b/Neos.Flow/Tests/Unit/Mvc/Routing/Fixtures/MockRoutePartHandler.php
index bbce2934b2..72f30e3cec 100644
--- a/Neos.Flow/Tests/Unit/Mvc/Routing/Fixtures/MockRoutePartHandler.php
+++ b/Neos.Flow/Tests/Unit/Mvc/Routing/Fixtures/MockRoutePartHandler.php
@@ -30,7 +30,7 @@ class MockRoutePartHandler extends DynamicRoutePart
      */
     private $resolveValueClosure;
 
-    public function __construct(\Closure $matchValueClosure = null, \Closure $resolveValueClosure = null)
+    public function __construct(?\Closure $matchValueClosure = null, ?\Closure $resolveValueClosure = null)
     {
         $this->matchValueClosure = $matchValueClosure;
         $this->resolveValueClosure = $resolveValueClosure;
diff --git a/Neos.Flow/Tests/Unit/Reflection/Fixture/Model/EntityWithDoctrineProxy.php b/Neos.Flow/Tests/Unit/Reflection/Fixture/Model/EntityWithDoctrineProxy.php
index bf285f1f8c..aea1b7a3e9 100644
--- a/Neos.Flow/Tests/Unit/Reflection/Fixture/Model/EntityWithDoctrineProxy.php
+++ b/Neos.Flow/Tests/Unit/Reflection/Fixture/Model/EntityWithDoctrineProxy.php
@@ -78,7 +78,7 @@ public function __setInitialized($initialized)
      * {@inheritDoc}
      * @internal generated method: use only when explicitly handling proxy specific loading logic
      */
-    public function __setInitializer(\Closure $initializer = null)
+    public function __setInitializer(?\Closure $initializer = null)
     {
         $this->__initializer__ = $initializer;
     }
@@ -96,7 +96,7 @@ public function __getInitializer()
      * {@inheritDoc}
      * @internal generated method: use only when explicitly handling proxy specific loading logic
      */
-    public function __setCloner(\Closure $cloner = null)
+    public function __setCloner(?\Closure $cloner = null)
     {
         $this->__cloner__ = $cloner;
     }
diff --git a/Neos.FluidAdaptor/Classes/Command/DocumentationCommandController.php b/Neos.FluidAdaptor/Classes/Command/DocumentationCommandController.php
index 496967fa59..dadb54af0f 100644
--- a/Neos.FluidAdaptor/Classes/Command/DocumentationCommandController.php
+++ b/Neos.FluidAdaptor/Classes/Command/DocumentationCommandController.php
@@ -45,7 +45,7 @@ class DocumentationCommandController extends CommandController
      * @param string $xsdDomain Domain used in the XSD schema (for example "http://yourdomain.org"). Defaults to "https://neos.io".
      * @return void
      */
-    public function generateXsdCommand(string $phpNamespace, string $xsdNamespace = null, string $targetFile = null, string $xsdDomain = ''): void
+    public function generateXsdCommand(string $phpNamespace, ?string $xsdNamespace = null, ?string $targetFile = null, string $xsdDomain = ''): void
     {
         $xsdDomain = trim($xsdDomain);
         $parsedDomain = parse_url($xsdDomain);
diff --git a/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php b/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
index 7c2a3219eb..09c9105e79 100644
--- a/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
+++ b/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
@@ -123,7 +123,7 @@ public static function createWithOptions(array $options)
      * @param array $options
      * @throws Exception
      */
-    public function __construct(array $options = null)
+    public function __construct(?array $options = null)
     {
         if ($options === null) {
             $options = [];
diff --git a/Neos.FluidAdaptor/Classes/View/StandaloneView.php b/Neos.FluidAdaptor/Classes/View/StandaloneView.php
index 7ab1890252..6d10c1f27e 100644
--- a/Neos.FluidAdaptor/Classes/View/StandaloneView.php
+++ b/Neos.FluidAdaptor/Classes/View/StandaloneView.php
@@ -79,7 +79,7 @@ public static function createWithOptions(array $options)
      * @param array $options
      * @throws \Neos\FluidAdaptor\Exception
      */
-    public function __construct(ActionRequest $request = null, array $options = [])
+    public function __construct(?ActionRequest $request = null, array $options = [])
     {
         $this->request = $request;
         parent::__construct($options);
diff --git a/Neos.FluidAdaptor/Tests/Functional/Form/Fixtures/Controller/FormController.php b/Neos.FluidAdaptor/Tests/Functional/Form/Fixtures/Controller/FormController.php
index 44455d57ca..68a6fc5768 100644
--- a/Neos.FluidAdaptor/Tests/Functional/Form/Fixtures/Controller/FormController.php
+++ b/Neos.FluidAdaptor/Tests/Functional/Form/Fixtures/Controller/FormController.php
@@ -44,7 +44,7 @@ public function createAction(\Neos\FluidAdaptor\Tests\Functional\Form\Fixtures\D
      * @return void
      * @Flow\IgnoreValidation("$fooPost")
      */
-    public function editAction(\Neos\FluidAdaptor\Tests\Functional\Form\Fixtures\Domain\Model\Post $fooPost = null)
+    public function editAction(?\Neos\FluidAdaptor\Tests\Functional\Form\Fixtures\Domain\Model\Post $fooPost = null)
     {
         $this->view->assign('fooPost', $fooPost);
     }
diff --git a/Neos.FluidAdaptor/Tests/Functional/View/Fixtures/View/StandaloneView.php b/Neos.FluidAdaptor/Tests/Functional/View/Fixtures/View/StandaloneView.php
index 21a3ddefd9..a559075829 100644
--- a/Neos.FluidAdaptor/Tests/Functional/View/Fixtures/View/StandaloneView.php
+++ b/Neos.FluidAdaptor/Tests/Functional/View/Fixtures/View/StandaloneView.php
@@ -25,7 +25,7 @@ class StandaloneView extends \Neos\FluidAdaptor\View\StandaloneView
      * @param string $fileIdentifierPrefix
      * @param array $options
      */
-    public function __construct(\Neos\Flow\Mvc\ActionRequest $request = null, $fileIdentifierPrefix = '', array $options = [])
+    public function __construct(?\Neos\Flow\Mvc\ActionRequest $request = null, $fileIdentifierPrefix = '', array $options = [])
     {
         $this->fileIdentifierPrefix = $fileIdentifierPrefix;
         parent::__construct($request, $options);
diff --git a/Neos.FluidAdaptor/Tests/Unit/View/TemplatePathsTest.php b/Neos.FluidAdaptor/Tests/Unit/View/TemplatePathsTest.php
index e8bb182e20..25675dcd0c 100644
--- a/Neos.FluidAdaptor/Tests/Unit/View/TemplatePathsTest.php
+++ b/Neos.FluidAdaptor/Tests/Unit/View/TemplatePathsTest.php
@@ -452,7 +452,7 @@ public function expandGenericPathPatternDataProvider()
      * @param string $pattern
      * @param string $expectedResult
      */
-    public function expandGenericPathPatternTests($package, $subPackage, $controller, $format, $templateRootPath, array $templateRootPaths = null, $partialRootPath, array $partialRootPaths = null, $layoutRootPath, array $layoutRootPaths = null, $bubbleControllerAndSubpackage, $formatIsOptional, $pattern, $expectedResult)
+    public function expandGenericPathPatternTests($package, $subPackage, $controller, $format, $templateRootPath, ?array $templateRootPaths = null, $partialRootPath, ?array $partialRootPaths = null, $layoutRootPath, ?array $layoutRootPaths = null, $bubbleControllerAndSubpackage, $formatIsOptional, $pattern, $expectedResult)
     {
         $options = [];
         if ($templateRootPath !== null) {
diff --git a/Neos.Http.Factories/Classes/UploadedFileFactoryTrait.php b/Neos.Http.Factories/Classes/UploadedFileFactoryTrait.php
index efee1158a9..f9ed53cc5f 100644
--- a/Neos.Http.Factories/Classes/UploadedFileFactoryTrait.php
+++ b/Neos.Http.Factories/Classes/UploadedFileFactoryTrait.php
@@ -15,7 +15,7 @@ trait UploadedFileFactoryTrait
     /**
      * @inheritDoc
      */
-    public function createUploadedFile(StreamInterface $stream, int $size = null, int $error = \UPLOAD_ERR_OK, string $clientFilename = null, string $clientMediaType = null): UploadedFileInterface
+    public function createUploadedFile(StreamInterface $stream, ?int $size = null, int $error = \UPLOAD_ERR_OK, ?string $clientFilename = null, ?string $clientMediaType = null): UploadedFileInterface
     {
         return new FlowUploadedFile($stream, $size ?: 0, $error, $clientFilename, $clientMediaType);
     }
diff --git a/Neos.Utility.Files/Classes/Files.php b/Neos.Utility.Files/Classes/Files.php
index f280e9e0cb..b0ff9b5b91 100644
--- a/Neos.Utility.Files/Classes/Files.php
+++ b/Neos.Utility.Files/Classes/Files.php
@@ -86,7 +86,7 @@ public static function concatenatePaths(array $paths): string
      * @return array Filenames including full path
      * @api
      */
-    public static function readDirectoryRecursively(string $path, string $suffix = null, bool $returnRealPath = false, bool $returnDotFiles = false): array
+    public static function readDirectoryRecursively(string $path, ?string $suffix = null, bool $returnRealPath = false, bool $returnDotFiles = false): array
     {
         return iterator_to_array(self::getRecursiveDirectoryGenerator($path, $suffix, $returnRealPath, $returnDotFiles));
     }
@@ -99,7 +99,7 @@ public static function readDirectoryRecursively(string $path, string $suffix = n
      * @return \Generator
      * @throws FilesException
      */
-    public static function getRecursiveDirectoryGenerator(string $path, string $suffix = null, bool $returnRealPath = false, bool $returnDotFiles = false)
+    public static function getRecursiveDirectoryGenerator(string $path, ?string $suffix = null, bool $returnRealPath = false, bool $returnDotFiles = false)
     {
         if (!is_dir($path)) {
             throw new FilesException('"' . $path . '" is no directory.', 1207253462);
@@ -177,7 +177,7 @@ public static function emptyDirectoryRecursively(string $path)
      * @api
      * @throws FilesException
      */
-    public static function removeEmptyDirectoriesOnPath(string $path, string $basePath = null)
+    public static function removeEmptyDirectoriesOnPath(string $path, ?string $basePath = null)
     {
         if ($basePath !== null) {
             $basePath = rtrim($basePath, '/');
@@ -444,7 +444,7 @@ public static function unlink(string $pathAndFilename): bool
      * @param string $thousandsSeparator thousands separator of the resulting string
      * @return string the size string, e.g. "1,024 MB"
      */
-    public static function bytesToSizeString($bytes, int $decimals = null, string $decimalSeparator = null, string $thousandsSeparator = null): string
+    public static function bytesToSizeString($bytes, ?int $decimals = null, ?string $decimalSeparator = null, ?string $thousandsSeparator = null): string
     {
         if (!is_int($bytes) && !is_float($bytes)) {
             if (is_numeric($bytes)) {
diff --git a/Neos.Utility.MediaTypes/Tests/Unit/MediaTypesTest.php b/Neos.Utility.MediaTypes/Tests/Unit/MediaTypesTest.php
index 89b1f9d73c..e71c8a78ba 100644
--- a/Neos.Utility.MediaTypes/Tests/Unit/MediaTypesTest.php
+++ b/Neos.Utility.MediaTypes/Tests/Unit/MediaTypesTest.php
@@ -170,7 +170,7 @@ public function mediaTypesWithAndWithoutParameters()
      * @test
      * @dataProvider mediaTypesWithAndWithoutParameters
      */
-    public function trimMediaTypeReturnsJustTheTypeAndSubTypeWithoutParameters(string $mediaType, string $expectedResult = null)
+    public function trimMediaTypeReturnsJustTheTypeAndSubTypeWithoutParameters(string $mediaType, ?string $expectedResult = null)
     {
         $actualResult = MediaTypes::trimMediaType($mediaType);
         self::assertSame($expectedResult, $actualResult);
diff --git a/Neos.Utility.ObjectHandling/Tests/Unit/Fixture/Model/EntityWithDoctrineProxy.php b/Neos.Utility.ObjectHandling/Tests/Unit/Fixture/Model/EntityWithDoctrineProxy.php
index b1a2a5d3f8..d176fa3a3f 100644
--- a/Neos.Utility.ObjectHandling/Tests/Unit/Fixture/Model/EntityWithDoctrineProxy.php
+++ b/Neos.Utility.ObjectHandling/Tests/Unit/Fixture/Model/EntityWithDoctrineProxy.php
@@ -90,7 +90,7 @@ public function __setInitialized($initialized)
      * {@inheritDoc}
      * @internal generated method: use only when explicitly handling proxy specific loading logic
      */
-    public function __setInitializer(\Closure $initializer = null)
+    public function __setInitializer(?\Closure $initializer = null)
     {
         $this->__initializer__ = $initializer;
     }
@@ -108,7 +108,7 @@ public function __getInitializer()
      * {@inheritDoc}
      * @internal generated method: use only when explicitly handling proxy specific loading logic
      */
-    public function __setCloner(\Closure $cloner = null)
+    public function __setCloner(?\Closure $cloner = null)
     {
         $this->__cloner__ = $cloner;
     }
diff --git a/Neos.Utility.OpcodeCache/Classes/OpcodeCacheHelper.php b/Neos.Utility.OpcodeCache/Classes/OpcodeCacheHelper.php
index 91504953be..aff36f3eca 100644
--- a/Neos.Utility.OpcodeCache/Classes/OpcodeCacheHelper.php
+++ b/Neos.Utility.OpcodeCache/Classes/OpcodeCacheHelper.php
@@ -83,7 +83,7 @@ protected static function initialize()
      * @param string $absolutePathAndFilename Absolute path towards the PHP file to clear.
      * @return void
      */
-    public static function clearAllActive(string $absolutePathAndFilename = null)
+    public static function clearAllActive(?string $absolutePathAndFilename = null)
     {
         if (self::$initialized === false) {
             self::initialize();
diff --git a/Neos.Utility.Unicode/Classes/Functions.php b/Neos.Utility.Unicode/Classes/Functions.php
index e9a38474b2..a13429ebb5 100644
--- a/Neos.Utility.Unicode/Classes/Functions.php
+++ b/Neos.Utility.Unicode/Classes/Functions.php
@@ -46,7 +46,7 @@ public static function strtotitle(string $string): string
      * @return string The processed string
      * @api
      */
-    public static function substr(string $string, int $start, int $length = null)
+    public static function substr(string $string, int $start, ?int $length = null)
     {
         if ($length === 0) {
             return '';
@@ -158,7 +158,7 @@ public static function strpos(string $haystack, string $needle, int $offset = 0)
      * @return string|array
      * @api
      */
-    public static function pathinfo(string $path, int $options = null)
+    public static function pathinfo(string $path, ?int $options = null)
     {
         $currentLocale = setlocale(LC_CTYPE, 0);
         // Before we have a setting for setlocale, his should suffice for pathinfo