diff --git a/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphFactory.php b/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphFactory.php
index 2599353780a..5f1b45b09a5 100644
--- a/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphFactory.php
+++ b/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /*
  * This file is part of the Neos.ContentGraph.DoctrineDbalAdapter package.
  *
diff --git a/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphTableNames.php b/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphTableNames.php
index 0804d77e7e0..82ec0d0b389 100644
--- a/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphTableNames.php
+++ b/Neos.ContentGraph.DoctrineDbalAdapter/src/ContentGraphTableNames.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\DoctrineDbalAdapter;
 
 use Neos\ContentRepository\Core\SharedModel\ContentRepository\ContentRepositoryId;
diff --git a/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalContentGraphSchemaBuilder.php b/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalContentGraphSchemaBuilder.php
index 1bce0351273..1a31b800538 100644
--- a/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalContentGraphSchemaBuilder.php
+++ b/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalContentGraphSchemaBuilder.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\DoctrineDbalAdapter;
 
 use Doctrine\DBAL\Exception as DBALException;
diff --git a/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalProjectionIntegrityViolationDetectionRunnerFactory.php b/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalProjectionIntegrityViolationDetectionRunnerFactory.php
index 377d74683fa..4b014684b8d 100644
--- a/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalProjectionIntegrityViolationDetectionRunnerFactory.php
+++ b/Neos.ContentGraph.DoctrineDbalAdapter/src/DoctrineDbalProjectionIntegrityViolationDetectionRunnerFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\DoctrineDbalAdapter;
 
 use Doctrine\DBAL\Connection;
diff --git a/Neos.ContentGraph.DoctrineDbalAdapter/src/NodeQueryBuilder.php b/Neos.ContentGraph.DoctrineDbalAdapter/src/NodeQueryBuilder.php
index 08848c98681..cfac70743cc 100644
--- a/Neos.ContentGraph.DoctrineDbalAdapter/src/NodeQueryBuilder.php
+++ b/Neos.ContentGraph.DoctrineDbalAdapter/src/NodeQueryBuilder.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\DoctrineDbalAdapter;
 
 use Doctrine\DBAL\ArrayParameterType;
diff --git a/Neos.ContentGraph.PostgreSQLAdapter/src/ContentHyperGraphFactory.php b/Neos.ContentGraph.PostgreSQLAdapter/src/ContentHyperGraphFactory.php
index 55b8b529a80..974c84d17ca 100644
--- a/Neos.ContentGraph.PostgreSQLAdapter/src/ContentHyperGraphFactory.php
+++ b/Neos.ContentGraph.PostgreSQLAdapter/src/ContentHyperGraphFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\PostgreSQLAdapter;
 
 use Doctrine\DBAL\Connection;
diff --git a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/HypergraphSchemaBuilder.php b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/HypergraphSchemaBuilder.php
index 40176222de6..d1a0e34c72e 100644
--- a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/HypergraphSchemaBuilder.php
+++ b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/HypergraphSchemaBuilder.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\PostgreSQLAdapter\Domain\Projection\SchemaBuilder;
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
diff --git a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/JsonbType.php b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/JsonbType.php
index b17ba8c50c7..ba4dca74eed 100644
--- a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/JsonbType.php
+++ b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/JsonbType.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\PostgreSQLAdapter\Domain\Projection\SchemaBuilder;
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
diff --git a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidArrayType.php b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidArrayType.php
index 7c5f6037994..f63d5515e2a 100644
--- a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidArrayType.php
+++ b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidArrayType.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\PostgreSQLAdapter\Domain\Projection\SchemaBuilder;
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
diff --git a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidType.php b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidType.php
index 94569f07f64..ffb813ca09d 100644
--- a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidType.php
+++ b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/UuidType.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\PostgreSQLAdapter\Domain\Projection\SchemaBuilder;
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
diff --git a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/VarcharArrayType.php b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/VarcharArrayType.php
index 316a2ce8f64..fbbff8ab64a 100644
--- a/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/VarcharArrayType.php
+++ b/Neos.ContentGraph.PostgreSQLAdapter/src/Domain/Projection/SchemaBuilder/VarcharArrayType.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentGraph\PostgreSQLAdapter\Domain\Projection\SchemaBuilder;
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
diff --git a/Neos.ContentRepository.BehavioralTests/Classes/PhpstanRules/DeclareStrictTypesRule.php b/Neos.ContentRepository.BehavioralTests/Classes/PhpstanRules/DeclareStrictTypesRule.php
new file mode 100644
index 00000000000..85f03b8f208
--- /dev/null
+++ b/Neos.ContentRepository.BehavioralTests/Classes/PhpstanRules/DeclareStrictTypesRule.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Neos\ContentRepository\BehavioralTests\PhpstanRules;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Node\FileNode;
+use PHPStan\Rules\Rule;
+
+/**
+ * @implements Rule<FileNode>
+ */
+class DeclareStrictTypesRule implements Rule
+{
+    public function getNodeType(): string
+    {
+        return FileNode::class;
+    }
+
+    public function processNode(Node $node, Scope $scope): array
+    {
+        assert($node instanceof FileNode);
+        $nodes = $node->getNodes();
+        if (0 === \count($nodes)) {
+            return [];
+        }
+        $firstNode = \array_shift($nodes);
+
+        if ($firstNode instanceof Node\Stmt\Declare_) {
+            foreach ($firstNode->declares as $declare) {
+                if (
+                    $declare->value instanceof Node\Scalar\LNumber
+                    && $declare->key->toLowerString() === 'strict_types'
+                    && $declare->value->value === 1
+                ) {
+                    return [];
+                }
+            }
+        }
+
+        return [
+            'File is missing a "declare(strict_types=1)" declaration.',
+        ];
+    }
+}
diff --git a/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceFactoryInterface.php b/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceFactoryInterface.php
index 3d6923659e0..fdcb1bf7d39 100644
--- a/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceFactoryInterface.php
+++ b/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceFactoryInterface.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Factory;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceInterface.php b/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceInterface.php
index 685f82137ae..f9c16c5772f 100644
--- a/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceInterface.php
+++ b/Neos.ContentRepository.Core/Classes/Factory/ContentRepositoryServiceInterface.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Factory;
 
 use Neos\ContentRepository\Core\ContentRepository;
diff --git a/Neos.ContentRepository.Core/Classes/Factory/ProjectionsAndCatchUpHooksFactory.php b/Neos.ContentRepository.Core/Classes/Factory/ProjectionsAndCatchUpHooksFactory.php
index 28e7fd6f27d..609afd289a8 100644
--- a/Neos.ContentRepository.Core/Classes/Factory/ProjectionsAndCatchUpHooksFactory.php
+++ b/Neos.ContentRepository.Core/Classes/Factory/ProjectionsAndCatchUpHooksFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Factory;
 
 use Neos\ContentRepository\Core\Projection\CatchUpHookFactories;
diff --git a/Neos.ContentRepository.Core/Classes/Feature/NodeDuplication/Dto/NodeAggregateIdMapping.php b/Neos.ContentRepository.Core/Classes/Feature/NodeDuplication/Dto/NodeAggregateIdMapping.php
index 723748937aa..1c5be536e61 100644
--- a/Neos.ContentRepository.Core/Classes/Feature/NodeDuplication/Dto/NodeAggregateIdMapping.php
+++ b/Neos.ContentRepository.Core/Classes/Feature/NodeDuplication/Dto/NodeAggregateIdMapping.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Feature\NodeDuplication\Dto;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/NodeType/ConstraintCheck.php b/Neos.ContentRepository.Core/Classes/NodeType/ConstraintCheck.php
index 978e3dd8948..5e6983c287e 100644
--- a/Neos.ContentRepository.Core/Classes/NodeType/ConstraintCheck.php
+++ b/Neos.ContentRepository.Core/Classes/NodeType/ConstraintCheck.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\NodeType;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/Projection/CatchUpHookInterface.php b/Neos.ContentRepository.Core/Classes/Projection/CatchUpHookInterface.php
index b487fc21b72..fbdfed6e8d5 100644
--- a/Neos.ContentRepository.Core/Classes/Projection/CatchUpHookInterface.php
+++ b/Neos.ContentRepository.Core/Classes/Projection/CatchUpHookInterface.php
@@ -1,9 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Projection;
 
 use Neos\ContentRepository\Core\EventStore\EventInterface;
-use Neos\EventStore\CatchUp\CheckpointStorageInterface;
 use Neos\EventStore\Model\EventEnvelope;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/Projection/CheckpointStorageStatus.php b/Neos.ContentRepository.Core/Classes/Projection/CheckpointStorageStatus.php
index 373628b32fa..fa33d6bf930 100644
--- a/Neos.ContentRepository.Core/Classes/Projection/CheckpointStorageStatus.php
+++ b/Neos.ContentRepository.Core/Classes/Projection/CheckpointStorageStatus.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Projection;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/Projection/DelegatingCatchUpHook.php b/Neos.ContentRepository.Core/Classes/Projection/DelegatingCatchUpHook.php
index 48b6ed2bef4..3edc73b751d 100644
--- a/Neos.ContentRepository.Core/Classes/Projection/DelegatingCatchUpHook.php
+++ b/Neos.ContentRepository.Core/Classes/Projection/DelegatingCatchUpHook.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Projection;
 
 use Neos\ContentRepository\Core\EventStore\EventInterface;
diff --git a/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatus.php b/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatus.php
index bcf9399ead0..517c53d7a7c 100644
--- a/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatus.php
+++ b/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatus.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Projection;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatusType.php b/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatusType.php
index 33c7e79c9cc..48681927742 100644
--- a/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatusType.php
+++ b/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatusType.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Projection;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatuses.php b/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatuses.php
index a1ee878837c..79a59b0a550 100644
--- a/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatuses.php
+++ b/Neos.ContentRepository.Core/Classes/Projection/ProjectionStatuses.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Projection;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/Projection/Workspace/WorkspaceStatus.php b/Neos.ContentRepository.Core/Classes/Projection/Workspace/WorkspaceStatus.php
index 12d3f36e864..8b0bb6590ae 100644
--- a/Neos.ContentRepository.Core/Classes/Projection/Workspace/WorkspaceStatus.php
+++ b/Neos.ContentRepository.Core/Classes/Projection/Workspace/WorkspaceStatus.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\Projection\Workspace;
 
 /**
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyDoesNotExist.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyDoesNotExist.php
index 06e534e7a95..7cc667ee842 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyDoesNotExist.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyDoesNotExist.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyExists.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyExists.php
index 850f205073e..038eee1caab 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyExists.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateCurrentlyExists.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsAmbiguous.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsAmbiguous.php
index af8c5e24719..2256dbdedbc 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsAmbiguous.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsAmbiguous.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsDescendant.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsDescendant.php
index ee3b3bffc5b..c2115ba93de 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsDescendant.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsDescendant.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsNotRoot.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsNotRoot.php
index b4f8689f5df..fffe6c5f841 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsNotRoot.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsNotRoot.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsRoot.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsRoot.php
index 9fefd0267b0..4f55e9710e9 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsRoot.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsRoot.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsTethered.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsTethered.php
index a3a6a5278d6..7238880dafd 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsTethered.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeAggregateIsTethered.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeNameIsAlreadyCovered.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeNameIsAlreadyCovered.php
index 03e5da36a1c..0506c3acb2e 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeNameIsAlreadyCovered.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeNameIsAlreadyCovered.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsAbstract.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsAbstract.php
index c230f290eaa..069ec1fc70e 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsAbstract.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsAbstract.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsNotOfTypeRoot.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsNotOfTypeRoot.php
index d3ff2ddab24..14b1f57e8ee 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsNotOfTypeRoot.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsNotOfTypeRoot.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsOfTypeRoot.php b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsOfTypeRoot.php
index 495988e0dc8..dc51115bfaf 100644
--- a/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsOfTypeRoot.php
+++ b/Neos.ContentRepository.Core/Classes/SharedModel/Exception/NodeTypeIsOfTypeRoot.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Core\SharedModel\Exception;
 
 /*
diff --git a/Neos.ContentRepository.Export/src/Exception/LiveWorkspaceContentStreamExistsException.php b/Neos.ContentRepository.Export/src/Exception/LiveWorkspaceContentStreamExistsException.php
index 183bc9778d8..98c9d220893 100644
--- a/Neos.ContentRepository.Export/src/Exception/LiveWorkspaceContentStreamExistsException.php
+++ b/Neos.ContentRepository.Export/src/Exception/LiveWorkspaceContentStreamExistsException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\Export\Exception;
 
 use Neos\Flow\Annotations as Flow;
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferenceNodesOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferenceNodesOperation.php
index 99013a906ce..212d919e6b5 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferenceNodesOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferenceNodesOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferencesOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferencesOperation.php
index 8056ab41891..33abeffcf9b 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferencesOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/BackReferencesOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ChildrenOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ChildrenOperation.php
index c28c110209a..f0da024527f 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ChildrenOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ChildrenOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ClosestOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ClosestOperation.php
index 7643e637141..68bc0d31e7b 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ClosestOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ClosestOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FilterOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FilterOperation.php
index 9b1107ddef4..7330664de5f 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FilterOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FilterOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FindOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FindOperation.php
index b34ac65895c..e81543cdc2a 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FindOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/FindOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/HasOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/HasOperation.php
index 0b01c624fbe..08f9a7623f3 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/HasOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/HasOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/IdOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/IdOperation.php
index 8d2a13fc4ed..16f66d77e86 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/IdOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/IdOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/LabelOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/LabelOperation.php
index 37e4a02df83..e987d2cc6d3 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/LabelOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/LabelOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextAllOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextAllOperation.php
index 72554d68337..dbee3b602ee 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextAllOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextAllOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextOperation.php
index e3db9f03141..483075dd43b 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextUntilOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextUntilOperation.php
index 9ca1494045a..a7416af823c 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextUntilOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NextUntilOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NodeTypeNameOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NodeTypeNameOperation.php
index 82d5770c315..8ff013d1dc5 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NodeTypeNameOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/NodeTypeNameOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentOperation.php
index 07790c7c64d..3c720f755a7 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsOperation.php
index 7d31223ef51..9cd016f1839 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsUntilOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsUntilOperation.php
index 76beab42acf..bebadfe442a 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsUntilOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ParentsUntilOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevAllOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevAllOperation.php
index cf4599636d4..87a7e57dd63 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevAllOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevAllOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevOperation.php
index 167fff1a12e..85f93b0cdec 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevUntilOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevUntilOperation.php
index bd7b854cfcd..bd13990151f 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevUntilOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PrevUntilOperation.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PropertyOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PropertyOperation.php
index c6b72e2dbe0..2b44d0b922f 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PropertyOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/PropertyOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferenceNodesOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferenceNodesOperation.php
index fd1ed47efd6..a9e6f350753 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferenceNodesOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferenceNodesOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencePropertyOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencePropertyOperation.php
index 94dcf618ac5..3f164a023bb 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencePropertyOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencePropertyOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencesOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencesOperation.php
index 1ae9a961ff7..f451d0f41c2 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencesOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/ReferencesOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/RemoveOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/RemoveOperation.php
index 44cd280351c..f4556679791 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/RemoveOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/RemoveOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/SiblingsOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/SiblingsOperation.php
index 8282af2b9f8..26c76b05965 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/SiblingsOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/SiblingsOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/UniqueOperation.php b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/UniqueOperation.php
index 16e12b2e837..4f51d808ea4 100644
--- a/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/UniqueOperation.php
+++ b/Neos.ContentRepository.NodeAccess/Classes/FlowQueryOperations/UniqueOperation.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepository\NodeAccess\FlowQueryOperations;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Command/ContentStreamCommandController.php b/Neos.ContentRepositoryRegistry/Classes/Command/ContentStreamCommandController.php
index 6cc56c336ee..7db24c23a9e 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Command/ContentStreamCommandController.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Command/ContentStreamCommandController.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Command;
 
 use Neos\ContentRepository\Core\Service\ContentStreamPrunerFactory;
diff --git a/Neos.ContentRepositoryRegistry/Classes/Command/NodeMigrationCommandController.php b/Neos.ContentRepositoryRegistry/Classes/Command/NodeMigrationCommandController.php
index ff3090e28ce..6b41a22537f 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Command/NodeMigrationCommandController.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Command/NodeMigrationCommandController.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Command;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Command/NodeTypesCommandController.php b/Neos.ContentRepositoryRegistry/Classes/Command/NodeTypesCommandController.php
index 71c62b4349f..5b8a40c6dbe 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Command/NodeTypesCommandController.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Command/NodeTypesCommandController.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Command;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Exception/ContentRepositoryNotFoundException.php b/Neos.ContentRepositoryRegistry/Classes/Exception/ContentRepositoryNotFoundException.php
index 69374b0ac2a..4f2a641c5cf 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Exception/ContentRepositoryNotFoundException.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Exception/ContentRepositoryNotFoundException.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Exception;
 
 use Neos\ContentRepository\Core\SharedModel\ContentRepository\ContentRepositoryId;
diff --git a/Neos.ContentRepositoryRegistry/Classes/Exception/InvalidConfigurationException.php b/Neos.ContentRepositoryRegistry/Classes/Exception/InvalidConfigurationException.php
index ad6860d6d26..cfb2a9f3bb8 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Exception/InvalidConfigurationException.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Exception/InvalidConfigurationException.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Exception;
 
 use Neos\ContentRepository\Core\SharedModel\ContentRepository\ContentRepositoryId;
diff --git a/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/Configuration.php b/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/Configuration.php
index eac88b2f937..c5dda60f1ad 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/Configuration.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/Configuration.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Migration\Configuration;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/ConfigurationInterface.php b/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/ConfigurationInterface.php
index 42c089e1599..cf2a00a2312 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/ConfigurationInterface.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/ConfigurationInterface.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Migration\Configuration;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/YamlConfiguration.php b/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/YamlConfiguration.php
index b70170772bd..8c9d35a05bf 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/YamlConfiguration.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Migration/Configuration/YamlConfiguration.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Migration\Configuration;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Migration/Factory/MigrationFactory.php b/Neos.ContentRepositoryRegistry/Classes/Migration/Factory/MigrationFactory.php
index 7ce03b09d58..0726fecac79 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Migration/Factory/MigrationFactory.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Migration/Factory/MigrationFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Migration\Factory;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Package.php b/Neos.ContentRepositoryRegistry/Classes/Package.php
index 771ce6a221d..00806fe1243 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Package.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Package.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry;
 
 /*
diff --git a/Neos.ContentRepositoryRegistry/Classes/Service/NodeMigrationGeneratorService.php b/Neos.ContentRepositoryRegistry/Classes/Service/NodeMigrationGeneratorService.php
index b96cb1a3226..817e6801325 100644
--- a/Neos.ContentRepositoryRegistry/Classes/Service/NodeMigrationGeneratorService.php
+++ b/Neos.ContentRepositoryRegistry/Classes/Service/NodeMigrationGeneratorService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\ContentRepositoryRegistry\Service;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/Cache/CacheSegmentParser.php b/Neos.Fusion/Classes/Core/Cache/CacheSegmentParser.php
index ffc544ec7c0..9e6234a2609 100644
--- a/Neos.Fusion/Classes/Core/Cache/CacheSegmentParser.php
+++ b/Neos.Fusion/Classes/Core/Cache/CacheSegmentParser.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\Cache;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/Cache/ContentCache.php b/Neos.Fusion/Classes/Core/Cache/ContentCache.php
index ed1e58c37b5..aaa712ff25d 100644
--- a/Neos.Fusion/Classes/Core/Cache/ContentCache.php
+++ b/Neos.Fusion/Classes/Core/Cache/ContentCache.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\Cache;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/Cache/FileMonitorListener.php b/Neos.Fusion/Classes/Core/Cache/FileMonitorListener.php
index 37d2acd12e6..c958dd3eadd 100644
--- a/Neos.Fusion/Classes/Core/Cache/FileMonitorListener.php
+++ b/Neos.Fusion/Classes/Core/Cache/FileMonitorListener.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\Cache;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/Cache/RuntimeContentCache.php b/Neos.Fusion/Classes/Core/Cache/RuntimeContentCache.php
index f744fe46ef7..5bebf766548 100644
--- a/Neos.Fusion/Classes/Core/Cache/RuntimeContentCache.php
+++ b/Neos.Fusion/Classes/Core/Cache/RuntimeContentCache.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\Cache;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/DslInterface.php b/Neos.Fusion/Classes/Core/DslInterface.php
index ee39040d676..3b6e2a28e57 100644
--- a/Neos.Fusion/Classes/Core/DslInterface.php
+++ b/Neos.Fusion/Classes/Core/DslInterface.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/AbsorbingHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/AbsorbingHandler.php
index 29257c63ec5..0df06fd5a90 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/AbsorbingHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/AbsorbingHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/AbstractRenderingExceptionHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/AbstractRenderingExceptionHandler.php
index 811f0f46f39..f1e1ae270d5 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/AbstractRenderingExceptionHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/AbstractRenderingExceptionHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/BubblingHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/BubblingHandler.php
index 184d8ef7c4a..830f85c442e 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/BubblingHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/BubblingHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/ContextDependentHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/ContextDependentHandler.php
index 1e0bb3694e1..b4a0fb216e5 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/ContextDependentHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/ContextDependentHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/HtmlMessageHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/HtmlMessageHandler.php
index be714eeb74f..4a4f3cda194 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/HtmlMessageHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/HtmlMessageHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/PlainTextHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/PlainTextHandler.php
index 9b5a74be590..78a2fd450b3 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/PlainTextHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/PlainTextHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/ThrowingHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/ThrowingHandler.php
index 69fea5a0713..3fa3ef9d609 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/ThrowingHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/ThrowingHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/ExceptionHandlers/XmlCommentHandler.php b/Neos.Fusion/Classes/Core/ExceptionHandlers/XmlCommentHandler.php
index 64c1ecc09aa..18e4e972fda 100644
--- a/Neos.Fusion/Classes/Core/ExceptionHandlers/XmlCommentHandler.php
+++ b/Neos.Fusion/Classes/Core/ExceptionHandlers/XmlCommentHandler.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core\ExceptionHandlers;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/Runtime.php b/Neos.Fusion/Classes/Core/Runtime.php
index 76f12b0d016..ca2cae722e7 100644
--- a/Neos.Fusion/Classes/Core/Runtime.php
+++ b/Neos.Fusion/Classes/Core/Runtime.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core;
 
 /*
diff --git a/Neos.Fusion/Classes/Core/RuntimeFactory.php b/Neos.Fusion/Classes/Core/RuntimeFactory.php
index fc5d84bd757..634499cee11 100644
--- a/Neos.Fusion/Classes/Core/RuntimeFactory.php
+++ b/Neos.Fusion/Classes/Core/RuntimeFactory.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\Fusion\Core;
 
 /*
diff --git a/Neos.Media/Classes/Domain/Service/AssetSourceService.php b/Neos.Media/Classes/Domain/Service/AssetSourceService.php
index 43766fe9e7a..533fa6e533e 100644
--- a/Neos.Media/Classes/Domain/Service/AssetSourceService.php
+++ b/Neos.Media/Classes/Domain/Service/AssetSourceService.php
@@ -1,6 +1,6 @@
 <?php
 
-declare(strict_types = 1);
+declare(strict_types=1);
 
 namespace Neos\Media\Domain\Service;
 
diff --git a/Neos.Neos/Classes/Controller/Backend/MenuHelper.php b/Neos.Neos/Classes/Controller/Backend/MenuHelper.php
index 4c9988e3916..a1a0b96dc0c 100644
--- a/Neos.Neos/Classes/Controller/Backend/MenuHelper.php
+++ b/Neos.Neos/Classes/Controller/Backend/MenuHelper.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Controller\Backend;
 
 /*
diff --git a/Neos.Neos/Classes/Controller/Module/User/UserSettingsController.php b/Neos.Neos/Classes/Controller/Module/User/UserSettingsController.php
index 9208f4e5aa9..be978a93643 100644
--- a/Neos.Neos/Classes/Controller/Module/User/UserSettingsController.php
+++ b/Neos.Neos/Classes/Controller/Module/User/UserSettingsController.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Controller\Module\User;
 
 /*
@@ -215,7 +217,7 @@ public function deleteElectronicAddressAction(User $user, ElectronicAddress $ele
         $this->userService->updateUser($user);
 
         $this->addFlashMessage(
-            $this->translator->translateById('userSettings.electronicAddressRemoved.body', [htmlspecialchars($electronicAddress->getIdentifier()), htmlspecialchars($electronicAddress->getType()), htmlspecialchars($user->getName())], null, null, 'Modules', 'Neos.Neos'),
+            $this->translator->translateById('userSettings.electronicAddressRemoved.body', [htmlspecialchars($electronicAddress->getIdentifier()), htmlspecialchars($electronicAddress->getType()), htmlspecialchars((string)$user->getName())], null, null, 'Modules', 'Neos.Neos'),
             $this->translator->translateById('userSettings.electronicAddressRemoved.title', [], null, null, 'Modules', 'Neos.Neos'),
             Message::SEVERITY_NOTICE,
             [],
diff --git a/Neos.Neos/Classes/Domain/NodeLabel/ExpressionBasedNodeLabelGenerator.php b/Neos.Neos/Classes/Domain/NodeLabel/ExpressionBasedNodeLabelGenerator.php
index ae6c9a291bc..95ff8df9655 100644
--- a/Neos.Neos/Classes/Domain/NodeLabel/ExpressionBasedNodeLabelGenerator.php
+++ b/Neos.Neos/Classes/Domain/NodeLabel/ExpressionBasedNodeLabelGenerator.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Domain\NodeLabel;
 
 /*
diff --git a/Neos.Neos/Classes/Domain/Service/FusionConfigurationCache.php b/Neos.Neos/Classes/Domain/Service/FusionConfigurationCache.php
index f100424bdd6..90c5ba8b0d3 100644
--- a/Neos.Neos/Classes/Domain/Service/FusionConfigurationCache.php
+++ b/Neos.Neos/Classes/Domain/Service/FusionConfigurationCache.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Domain\Service;
 
 /*
diff --git a/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHook.php b/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHook.php
index 3c57bc02c14..e0081f19c13 100644
--- a/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHook.php
+++ b/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHook.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\FrontendRouting\CatchUpHook;
 
 use Neos\ContentRepository\Core\ContentRepository;
diff --git a/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHookFactory.php b/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHookFactory.php
index dda9b9eead6..15b92e86c39 100644
--- a/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHookFactory.php
+++ b/Neos.Neos/Classes/FrontendRouting/CatchUpHook/RouterCacheHookFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\FrontendRouting\CatchUpHook;
 
 use Neos\ContentRepository\Core\ContentRepository;
diff --git a/Neos.Neos/Classes/FrontendRouting/Projection/DocumentUriPathSchemaBuilder.php b/Neos.Neos/Classes/FrontendRouting/Projection/DocumentUriPathSchemaBuilder.php
index 742f5294386..a983f41fd26 100644
--- a/Neos.Neos/Classes/FrontendRouting/Projection/DocumentUriPathSchemaBuilder.php
+++ b/Neos.Neos/Classes/FrontendRouting/Projection/DocumentUriPathSchemaBuilder.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\FrontendRouting\Projection;
 
 use Doctrine\DBAL\Exception as DBALException;
diff --git a/Neos.Neos/Classes/Fusion/Cache/GraphProjectorCatchUpHookForCacheFlushingFactory.php b/Neos.Neos/Classes/Fusion/Cache/GraphProjectorCatchUpHookForCacheFlushingFactory.php
index 7dfa6022cd6..62e8c499008 100644
--- a/Neos.Neos/Classes/Fusion/Cache/GraphProjectorCatchUpHookForCacheFlushingFactory.php
+++ b/Neos.Neos/Classes/Fusion/Cache/GraphProjectorCatchUpHookForCacheFlushingFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Fusion\Cache;
 
 /*
diff --git a/Neos.Neos/Classes/Fusion/Helper/BackendHelper.php b/Neos.Neos/Classes/Fusion/Helper/BackendHelper.php
index 636cefd0958..39bd8d1ff64 100644
--- a/Neos.Neos/Classes/Fusion/Helper/BackendHelper.php
+++ b/Neos.Neos/Classes/Fusion/Helper/BackendHelper.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Fusion\Helper;
 
 /*
diff --git a/Neos.Neos/Classes/Service/XliffService.php b/Neos.Neos/Classes/Service/XliffService.php
index 4531e52cb78..33901e1bf0f 100644
--- a/Neos.Neos/Classes/Service/XliffService.php
+++ b/Neos.Neos/Classes/Service/XliffService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Service;
 
 /*
@@ -92,7 +94,7 @@ class XliffService
      */
     public function getCachedJson(Locale $locale): string
     {
-        $cacheIdentifier = md5($locale);
+        $cacheIdentifier = md5((string)$locale);
 
         if ($this->xliffToJsonTranslationsCache->has($cacheIdentifier)) {
             $json = $this->xliffToJsonTranslationsCache->get($cacheIdentifier);
diff --git a/Neos.Neos/Classes/Utility/User.php b/Neos.Neos/Classes/Utility/User.php
index 9ecaaf1d110..5275452f696 100644
--- a/Neos.Neos/Classes/Utility/User.php
+++ b/Neos.Neos/Classes/Utility/User.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\Utility;
 
 use Neos\Neos\Domain\Service\WorkspaceNameBuilder;
diff --git a/Neos.Neos/Classes/ViewHelpers/Node/LabelViewHelper.php b/Neos.Neos/Classes/ViewHelpers/Node/LabelViewHelper.php
index b3bbb0edfc4..7cd9a3c792a 100644
--- a/Neos.Neos/Classes/ViewHelpers/Node/LabelViewHelper.php
+++ b/Neos.Neos/Classes/ViewHelpers/Node/LabelViewHelper.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\Neos\ViewHelpers\Node;
 
 use Neos\ContentRepository\Core\Projection\ContentGraph\Node;
diff --git a/Neos.NodeTypes.Form/Classes/Service/DataSource/FormDefinitionDataSource.php b/Neos.NodeTypes.Form/Classes/Service/DataSource/FormDefinitionDataSource.php
index 75dddc29fef..fc4cecfc9cc 100644
--- a/Neos.NodeTypes.Form/Classes/Service/DataSource/FormDefinitionDataSource.php
+++ b/Neos.NodeTypes.Form/Classes/Service/DataSource/FormDefinitionDataSource.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Neos\NodeTypes\Form\Service\DataSource;
 
 /*
diff --git a/Neos.TimeableNodeVisibility/Classes/Command/TimeableNodeVisibilityCommandController.php b/Neos.TimeableNodeVisibility/Classes/Command/TimeableNodeVisibilityCommandController.php
index 2291e42f850..a635c99825d 100644
--- a/Neos.TimeableNodeVisibility/Classes/Command/TimeableNodeVisibilityCommandController.php
+++ b/Neos.TimeableNodeVisibility/Classes/Command/TimeableNodeVisibilityCommandController.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\TimeableNodeVisibility\Command;
 
 use Neos\ContentRepository\Core\SharedModel\ContentRepository\ContentRepositoryId;
diff --git a/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibilities.php b/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibilities.php
index 4e64be4ea52..ffec2fd02c0 100644
--- a/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibilities.php
+++ b/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibilities.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\TimeableNodeVisibility\Domain;
 
 /**
diff --git a/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibility.php b/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibility.php
index 132e99bf186..7051112f244 100644
--- a/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibility.php
+++ b/Neos.TimeableNodeVisibility/Classes/Domain/ChangedVisibility.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\TimeableNodeVisibility\Domain;
 
 use Neos\ContentRepository\Core\Projection\ContentGraph\Node;
diff --git a/Neos.TimeableNodeVisibility/Classes/Service/TimeableNodeVisibilityService.php b/Neos.TimeableNodeVisibility/Classes/Service/TimeableNodeVisibilityService.php
index e486163553e..47a40a73100 100644
--- a/Neos.TimeableNodeVisibility/Classes/Service/TimeableNodeVisibilityService.php
+++ b/Neos.TimeableNodeVisibility/Classes/Service/TimeableNodeVisibilityService.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Neos\TimeableNodeVisibility\Service;
 
 use Neos\ContentRepository\Core\ContentRepository;
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 470b5dbaa2e..61381d4aa24 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -28,3 +28,4 @@ parameters:
 rules:
     - Neos\ContentRepository\BehavioralTests\PhpstanRules\ApiOrInternalAnnotationRule
     - Neos\ContentRepository\BehavioralTests\PhpstanRules\InternalMethodsNotAllowedOutsideContentRepositoryRule
+    - Neos\ContentRepository\BehavioralTests\PhpstanRules\DeclareStrictTypesRule