diff --git a/Protocols/EPP/eppException.php b/Protocols/EPP/eppException.php
index 4f716736..1d49a8d8 100644
--- a/Protocols/EPP/eppException.php
+++ b/Protocols/EPP/eppException.php
@@ -29,7 +29,7 @@ class eppException extends \Exception {
      * @param string $command
      * @param \Metaregistrar\EPP\eppResponse|null $response
      */
-    public function __construct($message = "", $code = 0, \Exception $previous = null, $reason = null, $command = null, $response = null) {
+    public function __construct($message = "", $code = 0, ?\Exception $previous = null, $reason = null, $command = null, $response = null) {
         $this->reason = $reason;
         $trace = $this->getTrace();
         $this->class = null;
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppCreateContactExtension.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppCreateContactExtension.php
index 346bbe57..c96da17a 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppCreateContactExtension.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppCreateContactExtension.php
@@ -6,7 +6,7 @@ class atEppCreateContactExtension extends atEppExtensionChain
 {
     protected $atEppContact=null;
 
-    function __construct(atEppContact $atEppContact, atEppExtensionChain $additionalEppExtension=null) {
+    function __construct(atEppContact $atEppContact, ?atEppExtensionChain $additionalEppExtension=null) {
         if(!is_null($additionalEppExtension)) {
             parent::__construct($additionalEppExtension);
         }
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppDomainDeleteExtension.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppDomainDeleteExtension.php
index 72ac4714..416b1baa 100644
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppDomainDeleteExtension.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppDomainDeleteExtension.php
@@ -28,7 +28,7 @@ class atEppDomainDeleteExtension extends atEppExtensionChain
      * @param array $domainExtArguments
      * @param atEppExtensionChain|null $additionalEppExtension
      */
-    public function __construct(array $domainExtArguments=[], atEppExtensionChain $additionalEppExtension = null)
+    public function __construct(array $domainExtArguments=[], ?atEppExtensionChain $additionalEppExtension = null)
     {
         $this->validateExtensionChain($domainExtArguments);
         if (!is_null($additionalEppExtension))
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppExtensionChain.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppExtensionChain.php
index c3addc27..a68e6bf4 100644
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppExtensionChain.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppExtensionChain.php
@@ -11,7 +11,7 @@ abstract class atEppExtensionChain
 {
     protected $additionalEppExtension=null;
 
-    function __construct(atEppExtensionChain $additionalEppExtension=null) {
+    function __construct(?atEppExtensionChain $additionalEppExtension=null) {
 
         $this->additionalEppExtension = $additionalEppExtension;
     }
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppUpdateContactExtension.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppUpdateContactExtension.php
index 98d2e654..35728ef9 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppUpdateContactExtension.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppExtensions/atEppUpdateContactExtension.php
@@ -6,7 +6,7 @@ class atEppUpdateContactExtension extends atEppExtensionChain
 {
     protected $atEppContact=null;
 
-    function __construct(atEppContact $atEppContact, atEppExtensionChain $additionalEppExtension=null) {
+    function __construct(atEppContact $atEppContact, ?atEppExtensionChain $additionalEppExtension=null) {
         if(!is_null($additionalEppExtension)) {
             parent::__construct($additionalEppExtension);
         }
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateContactRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateContactRequest.php
index 1eff8fde..172cc65c 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateContactRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateContactRequest.php
@@ -7,7 +7,7 @@ class atEppCreateContactRequest extends eppCreateContactRequest {
 
     protected $atEppExtensionChain = null;
 
-    function __construct($createinfo,atEppExtensionChain $atEppExtensionChain=null) {
+    function __construct($createinfo,?atEppExtensionChain $atEppExtensionChain=null) {
         $this->atEppExtensionChain = $atEppExtensionChain;
        parent::__construct($createinfo);
        $this->addSessionId();
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateDomainRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateDomainRequest.php
index 4719be7e..45bf2d85 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppCreateDomainRequest.php
@@ -8,7 +8,7 @@ class atEppCreateDomainRequest extends eppCreateDomainRequest
 
     protected $atEppExtensionChain = null;
 
-    function __construct($createinfo,atEppExtensionChain $atEppExtensionChain=null, $forcehostattr = true) {
+    function __construct($createinfo,?atEppExtensionChain $atEppExtensionChain=null, $forcehostattr = true) {
         $this->atEppExtensionChain = $atEppExtensionChain;
         parent::__construct($createinfo,$forcehostattr);
     }
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteDomainRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteDomainRequest.php
index 5f56523a..2f3a8e1d 100644
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteDomainRequest.php
@@ -28,7 +28,7 @@ class atEppDeleteDomainRequest extends eppDeleteDomainRequest
     const SCHEDULE_DELETE_NOW = "now";
     const SCHEDULE_DELETE_EXPIRATION = "expiration";
 
-    function __construct(eppDomain $deleteinfo, $namespacesinroot = true, $scheduledate = self::SCHEDULE_DELETE_NOW, atEppExtensionChain $atEppExtensionChain=null) {
+    function __construct(eppDomain $deleteinfo, $namespacesinroot = true, $scheduledate = self::SCHEDULE_DELETE_NOW, ?atEppExtensionChain $atEppExtensionChain=null) {
         $this->atEppExtensionChain = $atEppExtensionChain;
         parent::__construct($deleteinfo, $namespacesinroot);
         $this->addATScheduledateExtension($scheduledate);
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteRequest.php
index a32b91d9..18c5bb8c 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppDeleteRequest.php
@@ -8,7 +8,7 @@ class atEppDeleteRequest extends eppDeleteRequest
 
     protected $atEppExtensionChain = null;
 
-    function __construct($deleteinfo, atEppExtensionChain $atEppExtensionChain = null) {
+    function __construct($deleteinfo, ?atEppExtensionChain $atEppExtensionChain = null) {
         $this->atEppExtensionChain = $atEppExtensionChain;
 
         parent::__construct($deleteinfo);
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppPollRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppPollRequest.php
index f3791118..8c111bb6 100644
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppPollRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppPollRequest.php
@@ -25,7 +25,7 @@ class atEppPollRequest extends eppPollRequest
 
     protected $atEppExtensionChain = null;
 
-    function __construct($polltype, $messageid = null, $services = null, atEppExtensionChain $atEppExtensionChain=null)
+    function __construct($polltype, $messageid = null, $services = null, ?atEppExtensionChain $atEppExtensionChain=null)
     {
         $this->atEppExtensionChain = $atEppExtensionChain;
         parent::__construct($polltype, $messageid, $services);
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppTransferRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppTransferRequest.php
index 54abcd7f..fae9534d 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppTransferRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppTransferRequest.php
@@ -8,7 +8,7 @@ class atEppTransferRequest extends eppTransferRequest
 
     protected $atEppExtensionChain = null;
 
-    function __construct($operation, $object,atEppExtensionChain $atEppExtensionChain=null)
+    function __construct($operation, $object,?atEppExtensionChain $atEppExtensionChain=null)
     {
         $this->atEppExtensionChain = $atEppExtensionChain;
         parent::__construct($operation, $object);
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUndeleteRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUndeleteRequest.php
index fc62f12f..8cb81a41 100644
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUndeleteRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUndeleteRequest.php
@@ -11,7 +11,7 @@ class atEppUndeleteRequest extends eppDomainRequest
      * @param eppDomain $domain
      * @param atEppExtensionChain|null $atEppExtensionChain
      */
-    function __construct(eppDomain $domain, atEppExtensionChain $atEppExtensionChain = null) {
+    function __construct(eppDomain $domain, ?atEppExtensionChain $atEppExtensionChain = null) {
         $this->atEppExtensionChain = $atEppExtensionChain;
 
         parent::__construct(eppRequest::TYPE_UPDATE);
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateContactRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateContactRequest.php
index 427dac69..eb085629 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateContactRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateContactRequest.php
@@ -7,7 +7,7 @@ class atEppUpdateContactRequest extends eppUpdateContactRequest
     use atEppCommandTrait;
     protected $atEppExtensionChain = null;
 
-    function __construct($objectname, atEppContact $addinfo = null, atEppContact $removeinfo = null,atEppContact $updateinfo = null,atEppExtensionChain $atEppExtensionChain=null) {
+    function __construct($objectname, ?atEppContact $addinfo = null, ?atEppContact $removeinfo = null,?atEppContact $updateinfo = null,?atEppExtensionChain $atEppExtensionChain=null) {
         $this->atEppExtensionChain = $atEppExtensionChain;
         parent::__construct($objectname, $addinfo , $removeinfo , $updateinfo);
         $this->addSessionId();
diff --git a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateDomainRequest.php b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateDomainRequest.php
index de766e0f..2e81f1e1 100755
--- a/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/at-ext-epp-1.0/eppRequests/atEppUpdateDomainRequest.php
@@ -8,7 +8,7 @@ class atEppUpdateDomainRequest extends eppUpdateDomainRequest
 
     protected $atEppExtensionChain = null;
 
-    function __construct($objectname, $addinfo = null, $removeinfo = null, $updateinfo = null, $forcehostattr=false,atEppExtensionChain $atEppExtensionChain=null)
+    function __construct($objectname, $addinfo = null, $removeinfo = null, $updateinfo = null, $forcehostattr=false,?atEppExtensionChain $atEppExtensionChain=null)
     {
         $this->atEppExtensionChain = $atEppExtensionChain;
         parent::__construct($objectname, $addinfo, $removeinfo, $updateinfo, $forcehostattr);
diff --git a/Protocols/EPP/eppExtensions/domain-ext-2.5/eppRequests/euridEppDeleteDomainRequest.php b/Protocols/EPP/eppExtensions/domain-ext-2.5/eppRequests/euridEppDeleteDomainRequest.php
index 8b752460..7aa36aeb 100644
--- a/Protocols/EPP/eppExtensions/domain-ext-2.5/eppRequests/euridEppDeleteDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/domain-ext-2.5/eppRequests/euridEppDeleteDomainRequest.php
@@ -21,7 +21,7 @@
 */
 
 class euridEppDeleteDomainRequest extends eppDeleteDomainRequest {
-    function __construct(eppDomain $deleteinfo, $namespacesinroot = true, \DateTime $deleteDate = null) {
+    function __construct(eppDomain $deleteinfo, $namespacesinroot = true, ?\DateTime $deleteDate = null) {
         parent::__construct($deleteinfo, $namespacesinroot);
         if($deleteDate !== null) {
             $this->addEURIDExtension($deleteDate->format('Y-m-d\TH:i:s\.\0\Z'));
diff --git a/Protocols/EPP/eppExtensions/ficora/eppRequests/ficoraEppUpdateDomainRequest.php b/Protocols/EPP/eppExtensions/ficora/eppRequests/ficoraEppUpdateDomainRequest.php
index cc313cac..a7c0f2c0 100644
--- a/Protocols/EPP/eppExtensions/ficora/eppRequests/ficoraEppUpdateDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/ficora/eppRequests/ficoraEppUpdateDomainRequest.php
@@ -4,7 +4,7 @@
 class ficoraEppUpdateDomainRequest extends eppUpdateDomainRequest {
 
     // Note: default value for $namespacesinroot differs from parent
-    public function __construct($objectname, ficoraEppDomain $addinfo = null, ficoraEppDomain $removeinfo = null, ficoraEppDomain $updateinfo = null, $forcehostattr=false, $namespacesinroot=false)
+    public function __construct($objectname, ?ficoraEppDomain $addinfo = null, ?ficoraEppDomain $removeinfo = null, ?ficoraEppDomain $updateinfo = null, $forcehostattr=false, $namespacesinroot=false)
     {
         parent::__construct($objectname, $addinfo, $removeinfo, $updateinfo, $forcehostattr, $namespacesinroot);
     }
diff --git a/Protocols/EPP/eppExtensions/sidn-ext-epp-1.0/eppExceptions/sidnEppException.php b/Protocols/EPP/eppExtensions/sidn-ext-epp-1.0/eppExceptions/sidnEppException.php
index f1d928ad..20a3f30a 100644
--- a/Protocols/EPP/eppExtensions/sidn-ext-epp-1.0/eppExceptions/sidnEppException.php
+++ b/Protocols/EPP/eppExtensions/sidn-ext-epp-1.0/eppExceptions/sidnEppException.php
@@ -31,7 +31,7 @@ class sidnEppException extends eppException {
      */
     private $eppresponse;
 
-    public function __construct($message = "", $code = 0, \Exception $previous = null, $reason = null, $command = null) {
+    public function __construct($message = "", $code = 0, ?\Exception $previous = null, $reason = null, $command = null) {
         if ($command) {
             $this->eppresponse = new eppResponse();
             $this->eppresponse->loadXML($command);
diff --git a/Protocols/EPP/eppExtensions/teleinfo/eppData/eppRealName.php b/Protocols/EPP/eppExtensions/teleinfo/eppData/eppRealName.php
index 78ef0209..2d6499a9 100644
--- a/Protocols/EPP/eppExtensions/teleinfo/eppData/eppRealName.php
+++ b/Protocols/EPP/eppExtensions/teleinfo/eppData/eppRealName.php
@@ -49,7 +49,7 @@ class eppRealName{
      * @param array  $documents
      * @param string $authorisationCode
      */
-    public function __construct(string $role=self::NAME_ROLE_PERSON, string $name='', string $number='', string $proof=self::NAME_PROOF_CITIZEN, array $documents=[], string $authorisationCode=null){
+    public function __construct(string $role=self::NAME_ROLE_PERSON, string $name='', string $number='', string $proof=self::NAME_PROOF_CITIZEN, array $documents=[], ?string $authorisationCode=null){
         !empty($role) && $this->setRole($role);
         !empty($name) && $this->setName($name);
         !empty($number) && $this->setNumber($number);
diff --git a/Protocols/EPP/eppExtensions/teleinfo/eppRequests/teleinfoEppInfoNameRequest.php b/Protocols/EPP/eppExtensions/teleinfo/eppRequests/teleinfoEppInfoNameRequest.php
index a3ed5c36..67273e2d 100644
--- a/Protocols/EPP/eppExtensions/teleinfo/eppRequests/teleinfoEppInfoNameRequest.php
+++ b/Protocols/EPP/eppExtensions/teleinfo/eppRequests/teleinfoEppInfoNameRequest.php
@@ -3,7 +3,7 @@
 
 class teleinfoEppInfoNameRequest extends teleinfoEppNameRequest {
 
-    function __construct(string $type, string $code, string $password=null) {
+    function __construct(string $type, string $code, ?string $password=null) {
         $this->setNamespacesinroot(false);
         parent::__construct(eppRequest::TYPE_INFO);
         if ($type!='signedCode' && $type!='input'){
diff --git a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppCreateDomainRequest.php b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppCreateDomainRequest.php
index 5d9a035e..9d50ef49 100644
--- a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppCreateDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppCreateDomainRequest.php
@@ -8,7 +8,7 @@ class verisignEppCreateDomainRequest extends eppCreateDomainRequest {
      *
      * @param eppDomain $domain
      */
-    public function __construct(eppDomain $domain, string $rnvc=null, string $dnvc=null, string $lang=null) {
+    public function __construct(eppDomain $domain, ?string $rnvc=null, ?string $dnvc=null, ?string $lang=null) {
         parent::__construct($domain);
         //add namestore extension
         $this->addNamestore($domain);
diff --git a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppExtension.php b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppExtension.php
index 2dc7a42b..a91e9754 100644
--- a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppExtension.php
+++ b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppExtension.php
@@ -13,7 +13,7 @@ trait verisignEppExtension{
      * @param eppDomain $domain
      * @author:Jansen <jansen.shi@qq.com>
      */
-    public function addNamestore(eppDomain $domain=null){
+    public function addNamestore(?eppDomain $domain=null){
         if ($domain instanceof eppDomain){
             $tld = substr(strrchr($domain->getDomainname(), '.'), 1);
         }else{
@@ -40,7 +40,7 @@ public function addIdnLang(string $lang='ENG'){
      * @param string $dnvc domain name verification code
      * @author:Jansen <jansen.shi@qq.com>
      */
-    public function addVerificationCode(string $rnvc=null, string $dnvc=null){
+    public function addVerificationCode(?string $rnvc=null, ?string $dnvc=null){
         //添加实名认证拓展
         $verifyExt = $this->createElement('verificationCode:encodedSignedCode');
         $verifyExt->setAttribute('xmlns:verificationCode', 'urn:ietf:params:xml:ns:verificationCode-1.0');
diff --git a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRealNameDomainRequest.php b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRealNameDomainRequest.php
index 563caa7a..2d70b4e4 100644
--- a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRealNameDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRealNameDomainRequest.php
@@ -10,7 +10,7 @@ class verisignEppRealNameDomainRequest extends eppDomainRequest {
      * @param string      $rnvc
      * @param string|null $dnvc
      */
-    public function __construct(eppDomain $domain, string $rnvc, string $dnvc=null) {
+    public function __construct(eppDomain $domain, string $rnvc, ?string $dnvc=null) {
         $this->setNamespacesinroot(true);
         $this->setForcehostattr(false);
         parent::__construct(eppRequest::TYPE_UPDATE);
diff --git a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRestoreDomainRequest.php b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRestoreDomainRequest.php
index 2537d9ee..66cdcc5f 100644
--- a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRestoreDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppRestoreDomainRequest.php
@@ -14,7 +14,7 @@ class verisignEppRestoreDomainRequest extends eppUpdateDomainRequest {
      * @param string $reason   赎回原因
      * @throws eppException
      */
-    public function __construct(string $op, eppDomain $domain, string $expire=null, string $reason=null){
+    public function __construct(string $op, eppDomain $domain, ?string $expire=null, ?string $reason=null){
         if (!in_array($op, [self::TYPE_REQUEST,self::TYPE_REPORT])){
             throw new eppException('The op attribute is invalid,only request or report is allow.');
         }
diff --git a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppTransferDomainRequest.php b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppTransferDomainRequest.php
index d31ae468..96884c54 100644
--- a/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppTransferDomainRequest.php
+++ b/Protocols/EPP/eppExtensions/verisign/eppRequests/verisignEppTransferDomainRequest.php
@@ -14,7 +14,7 @@ class verisignEppTransferDomainRequest extends eppTransferRequest {
      * @param string|null $lang
      * @throws eppException
      */
-    public function __construct(string $op, eppDomain $domain, string $rnvc=null, string $dnvc=null, string $lang=null) {
+    public function __construct(string $op, eppDomain $domain, ?string $rnvc=null, ?string $dnvc=null, ?string $lang=null) {
         parent::__construct($op, $domain);
         //add namestore extension
         $this->addNamestore($domain);
diff --git a/Protocols/EPP/eppResponses/eppResponse.php b/Protocols/EPP/eppResponses/eppResponse.php
index 9237bd75..c6bd620b 100644
--- a/Protocols/EPP/eppResponses/eppResponse.php
+++ b/Protocols/EPP/eppResponses/eppResponse.php
@@ -110,7 +110,7 @@ public function findNamespace($namespace) {
     }
 
     #[\ReturnTypeWillChange]
-    public function saveXML(\DOMNode $node = NULL, $options = NULL) {
+    public function saveXML(?\DOMNode $node = NULL, $options = NULL) {
         return str_replace("\t", '  ', parent::saveXML($node, LIBXML_NOEMPTYTAG));
     }
 
diff --git a/Protocols/TMCH/tmchData/tmchClaimData.php b/Protocols/TMCH/tmchData/tmchClaimData.php
index 48642f8e..b2004ff9 100644
--- a/Protocols/TMCH/tmchData/tmchClaimData.php
+++ b/Protocols/TMCH/tmchData/tmchClaimData.php
@@ -168,7 +168,7 @@ public function __destruct() {
      * @return mixed
      */
     #[\ReturnTypeWillChange]
-    public function saveXML(\DOMNode $node = null, $options = null) {
+    public function saveXML(?\DOMNode $node = null, $options = null) {
         return str_replace("\t", '  ', parent::saveXML($node, LIBXML_NOEMPTYTAG));
     }
 
diff --git a/Protocols/TMCH/tmchException.php b/Protocols/TMCH/tmchException.php
index e3eb56c7..ce027421 100644
--- a/Protocols/TMCH/tmchException.php
+++ b/Protocols/TMCH/tmchException.php
@@ -5,7 +5,7 @@ class tmchException extends \Exception {
     private $reason;
     private $id;
 
-    public function __construct($message = "", $code = 0, \Exception $previous = null, $reason = null, $id = null) {
+    public function __construct($message = "", $code = 0, ?\Exception $previous = null, $reason = null, $id = null) {
         $this->reason = $reason;
         $this->id = $id;
         parent::__construct($message, $code, $previous);
diff --git a/composer.json b/composer.json
index 7a7d1b6f..3ce6b323 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
         }
     ],
     "require": {
-        "php": "^7|^8.0",
+        "php": "^7.1|^8.0",
         "ext-dom": "*",
         "ext-libxml": "*"
     },