diff --git a/CHANGELOG.md b/CHANGELOG.md
index 48a6753..3ebeb77 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+# Version 2.1.0
+
+## Features
+
+### PHP 8.4 Compatibility
+
+* Add PHP 8.4 support
+
 # Version 2.0.0
 
 ### PHP 8.1 Compatibility
@@ -31,4 +39,4 @@
 
 ## Features
 
-* PAC-541: Update composer with php Version ">=^7.3"
\ No newline at end of file
+* PAC-541: Update composer with php Version ">=^7.3"
diff --git a/composer.json b/composer.json
index 5cde8f1..1063936 100755
--- a/composer.json
+++ b/composer.json
@@ -6,7 +6,7 @@
     "prefer-stable": true,
     "require": {
         "php": "^8.1",
-        "techdivision/import-serializer": "^2.0.0"
+        "techdivision/import-serializer": "^2.1"
     },
     "require-dev": {
         "doctrine/dbal": "^4.0.4",
@@ -33,4 +33,4 @@
             ]
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/AdditionalAttributeCsvSerializer.php b/src/AdditionalAttributeCsvSerializer.php
index 1383ace..42a8588 100644
--- a/src/AdditionalAttributeCsvSerializer.php
+++ b/src/AdditionalAttributeCsvSerializer.php
@@ -289,7 +289,7 @@ public function unserialize($serialized = null, $delimiter = null)
      * @return string The serialized array
      * @see \TechDivision\Import\Serializer\SerializerInterface::serialize()
      */
-    public function serialize(array $unserialized = null, $delimiter = null)
+    public function serialize(?array $unserialized = null, $delimiter = null)
     {
         return $this->getValueCsvSerializer()->implode($unserialized, $delimiter ? $delimiter : $this->getMultipleFieldDelimiter());
     }
@@ -319,7 +319,7 @@ public function explode($value = null, $delimiter = null)
      * @return string|null The compatected value
      * @see \TechDivision\Import\Serializer\SerializerInterface::serialize()
      */
-    public function implode(array $value = null, $delimiter = null)
+    public function implode(?array $value = null, $delimiter = null)
     {
         return $this->serialize($value, $delimiter);
     }
@@ -332,7 +332,7 @@ public function implode(array $value = null, $delimiter = null)
      *
      * @return array The array with the denormalized attribute values
      */
-    public function denormalize(string $value = null, bool $unpack = true) : array
+    public function denormalize(?string $value = null, bool $unpack = true) : array
     {
 
         // initialize the array for the attributes
diff --git a/src/CategoryCsvSerializer.php b/src/CategoryCsvSerializer.php
index da392ca..66bd019 100644
--- a/src/CategoryCsvSerializer.php
+++ b/src/CategoryCsvSerializer.php
@@ -167,7 +167,7 @@ public function explode($value = null, $delimiter = null)
      * @return string|null The compatected value
      * @see \TechDivision\Import\Serializer\SerializerInterface::serialize()
      */
-    public function implode(array $value = null, $delimiter = null)
+    public function implode(?array $value = null, $delimiter = null)
     {
         return $this->serialize($value, $delimiter);
     }
@@ -195,7 +195,7 @@ public function unserialize($serialized = null, $delimiter = null)
      * @return string The serialized array
      * @see \TechDivision\Import\Serializer\SerializerInterface::serialize()
      */
-    public function serialize(array $unserialized = null, $delimiter = null)
+    public function serialize(?array $unserialized = null, $delimiter = null)
     {
         return $this->getValueCsvSerializer()->implode($unserialized, $delimiter ? $delimiter : $this->getCategoryDelimiter());
     }
diff --git a/src/ProductCategoryCsvSerializer.php b/src/ProductCategoryCsvSerializer.php
index 11f67f7..5bf45e9 100644
--- a/src/ProductCategoryCsvSerializer.php
+++ b/src/ProductCategoryCsvSerializer.php
@@ -167,7 +167,7 @@ public function explode($value = null, $delimiter = null)
      * @return string|null The compatected value
      * @see \TechDivision\Import\Serializer\SerializerInterface::serialize()
      */
-    public function implode(array $value = null, $delimiter = null)
+    public function implode(?array $value = null, $delimiter = null)
     {
         return $this->serialize($value, $delimiter);
     }
@@ -195,7 +195,7 @@ public function unserialize($serialized = null, $delimiter = null)
      * @return string The serialized array
      * @see \TechDivision\Import\Serializer\SerializerInterface::serialize()
      */
-    public function serialize(array $unserialized = null, $delimiter = null)
+    public function serialize(?array $unserialized = null, $delimiter = null)
     {
         return $this->getValueCsvSerializer()->implode($unserialized, $delimiter);
     }
diff --git a/src/ValueCsvSerializer.php b/src/ValueCsvSerializer.php
index 6c666f8..2dbc2c2 100644
--- a/src/ValueCsvSerializer.php
+++ b/src/ValueCsvSerializer.php
@@ -63,7 +63,7 @@ protected function getDelimiter()
      *
      * @return string The serialized array
      */
-    public function serialize(array $unserialized = null, $delimiter = null)
+    public function serialize(?array $unserialized = null, $delimiter = null)
     {
 
         // do nothing, if the passed value is empty or NULL
@@ -153,7 +153,7 @@ public function explode($value = null, $delimiter = null)
      * @return string|null The compatected value
      * @see  \TechDivision\Import\Serializer\SerializerInterface::serialize()
      */
-    public function implode(array $value = null, $delimiter = null)
+    public function implode(?array $value = null, $delimiter = null)
     {
 
         // set the delimiter