diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index e5a5c860..5c2a3fd9 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -87,9 +87,11 @@ jobs:
       matrix:
         include:
           - php-version: '8.2'
-            typo3-version: '^13.2'
+            typo3-version: '^13.4'
           - php-version: '8.3'
-            typo3-version: '^13.2'
+            typo3-version: '^13.4'
+          - php-version: '8.4'
+            typo3-version: '^13.4'
     steps:
       - uses: actions/checkout@v4
 
@@ -126,9 +128,15 @@ jobs:
       - name: Run Unit Tests PHP8.3
         run: nix-shell --arg phpVersion \"php83\" --pure --run project-test-unit
 
+      - name: Run Unit Tests PHP8.4
+        run: nix-shell --arg phpVersion \"php84\" --pure --run project-test-unit
+
       - name: Run Functional Tests PHP8.2
         run: nix-shell --arg phpVersion \"php82\" --pure --run project-test-functional
 
       - name: Run Functional Tests PHP8.3
         run: nix-shell --arg phpVersion \"php83\" --pure --run project-test-functional
 
+      - name: Run Functional Tests PHP8.4
+        run: nix-shell --arg phpVersion \"php84\" --pure --run project-test-functional
+
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 86b46709..50fc0431 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -65,6 +65,11 @@ lint:php83:
   variables:
     CONTAINER_IMAGE: php:8.3-alpine
 
+lint:php84:
+  <<: *lint_php
+  variables:
+    CONTAINER_IMAGE: php:8.4-alpine
+
 phpstan:analyse:
   image: $CI_REGISTRY/containers/phpunit-with-php-8.2:main
   stage: lint
@@ -94,19 +99,26 @@ phpstan:analyse:
     - .build/bin/phpunit -c Build/UnitTests.xml
     - typo3DatabaseDriver=pdo_sqlite .build/bin/phpunit -c Build/FunctionalTests.xml
 
-# Build in PHP 8.2 and TYPO3 13.3
+# Build in PHP 8.2 and TYPO3 13.4
 test:php82:typo3_13:
   <<: *test_php
   variables:
     CONTAINER_IMAGE: $CI_REGISTRY/containers/phpunit-with-php-8.2:main
-    TYPO3_VERSION: ^13.3
+    TYPO3_VERSION: ^13.4
 
-# Build in PHP 8.3 and TYPO3 13.2
+# Build in PHP 8.3 and TYPO3 13.4
 test:php83:typo3_13:
   <<: *test_php
   variables:
     CONTAINER_IMAGE: $CI_REGISTRY/containers/phpunit-with-php-8.3:main
-    TYPO3_VERSION: ^13.3
+    TYPO3_VERSION: ^13.4
+
+# Build in PHP 8.4 and TYPO3 13.4
+test:php84:typo3_13:
+  <<: *test_php
+  variables:
+    CONTAINER_IMAGE: $CI_REGISTRY/containers/phpunit-with-php-8.4:main
+    TYPO3_VERSION: ^13.4
 
 documentation:
   stage: documentation
diff --git a/Classes/Controller/Cart/CartController.php b/Classes/Controller/Cart/CartController.php
index 5c9699e7..68281c0d 100755
--- a/Classes/Controller/Cart/CartController.php
+++ b/Classes/Controller/Cart/CartController.php
@@ -23,9 +23,9 @@
 class CartController extends ActionController
 {
     public function showAction(
-        Item $orderItem = null,
-        BillingAddress $billingAddress = null,
-        ShippingAddress $shippingAddress = null
+        ?Item $orderItem = null,
+        ?BillingAddress $billingAddress = null,
+        ?ShippingAddress $shippingAddress = null
     ): ResponseInterface {
         $this->restoreSession();
 
diff --git a/Classes/Controller/Cart/OrderController.php b/Classes/Controller/Cart/OrderController.php
index bf2226c3..fb01571d 100644
--- a/Classes/Controller/Cart/OrderController.php
+++ b/Classes/Controller/Cart/OrderController.php
@@ -57,9 +57,9 @@ public function initializeCreateAction(): void
 
     #[IgnoreValidation(['value' => 'shippingAddress'])]
     public function createAction(
-        Item $orderItem = null,
-        BillingAddress $billingAddress = null,
-        ShippingAddress $shippingAddress = null
+        ?Item $orderItem = null,
+        ?BillingAddress $billingAddress = null,
+        ?ShippingAddress $shippingAddress = null
     ): ResponseInterface {
         $this->restoreSession();
 
diff --git a/Classes/Controller/Cart/ProductController.php b/Classes/Controller/Cart/ProductController.php
index f3eca424..2950a1d6 100644
--- a/Classes/Controller/Cart/ProductController.php
+++ b/Classes/Controller/Cart/ProductController.php
@@ -14,7 +14,6 @@
 use Extcode\Cart\Domain\Model\Cart\Product;
 use Extcode\Cart\Event\CheckProductAvailabilityEvent;
 use Extcode\Cart\Event\RetrieveProductsFromRequestEvent;
-use Psr\EventDispatcher\EventDispatcherInterface;
 use Psr\Http\Message\ResponseInterface;
 use TYPO3\CMS\Core\Messaging\AbstractMessage;
 use TYPO3\CMS\Core\Type\ContextualFeedbackSeverity;
@@ -24,14 +23,6 @@ class ProductController extends ActionController
 {
     public const AJAX_CART_TYPE_NUM = '2278001';
 
-    public function __construct(
-        EventDispatcherInterface $eventDispatcher = null
-    ) {
-        if ($eventDispatcher !== null) {
-            $this->eventDispatcher = $eventDispatcher;
-        }
-    }
-
     public function addAction(): ResponseInterface
     {
         if (!$this->request->hasArgument('productType')) {
diff --git a/Classes/Domain/Model/Cart/BeVariant.php b/Classes/Domain/Model/Cart/BeVariant.php
index 43fd6300..0fff53a3 100644
--- a/Classes/Domain/Model/Cart/BeVariant.php
+++ b/Classes/Domain/Model/Cart/BeVariant.php
@@ -13,10 +13,6 @@
 
 class BeVariant
 {
-    protected ?Product $product = null;
-
-    protected ?BeVariant $parentBeVariant = null;
-
     protected string $titleDelimiter = ' - ';
 
     protected string $skuDelimiter = '-';
@@ -45,30 +41,13 @@ class BeVariant
 
     public function __construct(
         protected string $id,
-        Product $product = null,
-        self $beVariant = null,
+        protected self|Product $parent,
         protected string $title,
         protected string $sku,
         protected int $priceCalcMethod,
         protected float $price,
         protected int $quantity = 0
     ) {
-        if ($product === null && $beVariant === null) {
-            throw new \InvalidArgumentException();
-        }
-
-        if ($product != null && $beVariant != null) {
-            throw new \InvalidArgumentException();
-        }
-
-        if ($product !== null) {
-            $this->product = $product;
-        }
-
-        if ($beVariant !== null) {
-            $this->parentBeVariant = $beVariant;
-        }
-
         $this->reCalc();
     }
 
@@ -102,36 +81,28 @@ public function toArray(): array
         return $variantArr;
     }
 
-    public function getProduct(): ?Product
+    public function getParent(): self|Product
     {
-        return $this->product;
+        return $this->parent;
     }
 
-    public function setProduct(Product $product): void
+    public function setParent(self|Product $parent): void
     {
-        $this->product = $product;
+        $this->parent = $parent;
     }
 
-    public function getParentBeVariant(): ?self
+    public function getProduct(): Product
     {
-        return $this->parentBeVariant;
-    }
+        if ($this->parent instanceof Product) {
+            return $this->parent;
+        }
 
-    public function setParentBeVariant(self $parentBeVariant): void
-    {
-        $this->parentBeVariant = $parentBeVariant;
+        return $this->parent->getProduct();
     }
 
     public function isNetPrice(): bool
     {
-        if ($this->getParentBeVariant()) {
-            return $this->getParentBeVariant()->isNetPrice();
-        }
-        if ($this->getProduct()) {
-            return $this->getProduct()->isNetPrice();
-        }
-
-        return false;
+        return $this->parent->isNetPrice();
     }
 
     public function getId(): string
@@ -158,10 +129,10 @@ public function getCompleteTitle(): string
     {
         $title = '';
 
-        if ($this->getParentBeVariant()) {
-            $title = $this->getParentBeVariant()->getCompleteTitle();
-        } elseif ($this->getProduct()) {
-            $title = $this->getProduct()->getTitle();
+        if ($this->parent instanceof self) {
+            $title = $this->parent->getCompleteTitle();
+        } elseif ($this->parent instanceof Product) {
+            $title = $this->parent->getTitle();
         }
 
         if ($this->isFeVariant) {
@@ -178,8 +149,8 @@ public function getCompleteTitleWithoutProduct(): string
         $title = '';
         $titleDelimiter = '';
 
-        if ($this->getParentBeVariant()) {
-            $title = $this->getParentBeVariant()->getCompleteTitleWithoutProduct();
+        if ($this->parent instanceof self) {
+            $title = $this->parent->getCompleteTitleWithoutProduct();
             $titleDelimiter = $this->titleDelimiter;
         }
 
@@ -244,12 +215,12 @@ public function getPriceCalculated(): float
     {
         $price = $this->getBestPrice();
 
-        if ($this->getParentBeVariant()) {
-            $parentPrice = $this->getParentBeVariant()->getBestPrice();
-        } elseif ($this->getProduct()) {
-            $parentPrice = $this->getProduct()->getBestPrice($this->getQuantity());
+        if ($this->parent instanceof self) {
+            $parentPrice = $this->parent->getBestPrice();
+        } elseif ($this->parent instanceof Product) {
+            $parentPrice = $this->parent->getBestPrice($this->getQuantity());
         } else {
-            $parentPrice = 0;
+            $parentPrice = 0.0;
         }
 
         if ($this->priceCalcMethod === 0) {
@@ -285,15 +256,11 @@ public function getParentPrice(): float
             return 0.0;
         }
 
-        if ($this->getParentBeVariant()) {
-            return $this->getParentBeVariant()->getBestPrice();
+        if ($this->parent instanceof self) {
+            return $this->parent->getBestPrice();
         }
 
-        if ($this->getProduct()) {
-            return $this->getProduct()->getBestPrice($this->getQuantity());
-        }
-
-        return 0.0;
+        return $this->parent->getBestPrice($this->getQuantity());
     }
 
     public function setPrice(float $price): void
@@ -332,10 +299,10 @@ public function getCompleteSku(): string
     {
         $sku = '';
 
-        if ($this->getParentBeVariant()) {
-            $sku = $this->getParentBeVariant()->getCompleteSku();
-        } elseif ($this->getProduct()) {
-            $sku = $this->getProduct()->getSku();
+        if ($this->parent instanceof self) {
+            $sku = $this->parent->getCompleteSku();
+        } elseif ($this->parent instanceof Product) {
+            $sku = $this->parent->getSku();
         }
 
         if ($this->isFeVariant) {
@@ -353,8 +320,8 @@ public function getCompleteSkuWithoutProduct(): string
 
         $skuDelimiter = '';
 
-        if ($this->getParentBeVariant()) {
-            $sku = $this->getParentBeVariant()->getCompleteSkuWithoutProduct();
+        if ($this->parent instanceof self) {
+            $sku = $this->parent->getCompleteSkuWithoutProduct();
             $skuDelimiter = $this->titleDelimiter;
         }
 
@@ -416,14 +383,7 @@ public function getTax(): float
 
     public function getTaxClass(): ?TaxClass
     {
-        if ($this->getParentBeVariant()) {
-            return $this->getParentBeVariant()->getTaxClass();
-        }
-        if ($this->getProduct()) {
-            return $this->getProduct()->getTaxClass();
-        }
-
-        return null;
+        return $this->parent->getTaxClass();
     }
 
     public function setQuantity(int $newQuantity): void
diff --git a/Classes/Domain/Model/Cart/Cart.php b/Classes/Domain/Model/Cart/Cart.php
index 915929ab..3fe4589f 100644
--- a/Classes/Domain/Model/Cart/Cart.php
+++ b/Classes/Domain/Model/Cart/Cart.php
@@ -1111,7 +1111,7 @@ public function setCurrencySign(string $currencySign): void
         $this->currencySign = $currencySign;
     }
 
-    public function translatePrice(float $price = null): ?float
+    public function translatePrice(?float $price = null): ?float
     {
         if ($price !== null) {
             $price /= $this->getCurrencyTranslation();
diff --git a/Classes/Domain/Model/Cart/Extra.php b/Classes/Domain/Model/Cart/Extra.php
index 25756c12..7fd67f37 100644
--- a/Classes/Domain/Model/Cart/Extra.php
+++ b/Classes/Domain/Model/Cart/Extra.php
@@ -31,7 +31,7 @@ public function __construct(
         protected TaxClass $taxClass,
         protected bool $isNetPrice = false,
         protected string $extraType = '',
-        Service $service = null
+        ?Service $service = null
     ) {
         $this->service = $service;
 
diff --git a/Classes/Domain/Model/Cart/Product.php b/Classes/Domain/Model/Cart/Product.php
index 5095ac41..36a29a89 100644
--- a/Classes/Domain/Model/Cart/Product.php
+++ b/Classes/Domain/Model/Cart/Product.php
@@ -69,7 +69,7 @@ public function __construct(
         protected TaxClass $taxClass,
         protected int $quantity,
         protected bool $isNetPrice = false,
-        FeVariant $feVariant = null
+        ?FeVariant $feVariant = null
     ) {
         if ($feVariant) {
             $this->feVariant = $feVariant;
@@ -130,7 +130,7 @@ public function addBeVariant(BeVariant $newVariant): void
                 $variant->setQuantity($newQuantity);
             }
         } else {
-            $newVariant->setProduct($this);
+            $newVariant->setParent($this);
             $this->beVariants[$newVariantsId] = $newVariant;
         }
 
@@ -275,7 +275,7 @@ public function getQuantityDiscounts(): array
         return $this->quantityDiscounts;
     }
 
-    public function getQuantityDiscountPrice(int $quantity = null): float
+    public function getQuantityDiscountPrice(?int $quantity = null): float
     {
         $price = $this->getTranslatedPrice();
 
@@ -300,7 +300,7 @@ public function setQuantityDiscounts(array $quantityDiscounts): void
     /**
      * Returns Best Price (min of Price and Special Price)
      */
-    public function getBestPrice(int $quantity = null): ?float
+    public function getBestPrice(?int $quantity = null): ?float
     {
         $bestPrice = $this->getQuantityDiscountPrice($quantity);
 
diff --git a/Classes/EventListener/Order/Create/PersistOrder/Products.php b/Classes/EventListener/Order/Create/PersistOrder/Products.php
index cbd3536b..b23992ff 100644
--- a/Classes/EventListener/Order/Create/PersistOrder/Products.php
+++ b/Classes/EventListener/Order/Create/PersistOrder/Products.php
@@ -95,7 +95,7 @@ protected function addProductVariants(Product $product): void
 
     protected function addFeVariants(
         \Extcode\Cart\Domain\Model\Order\Product $product,
-        FeVariant $feVariant = null
+        ?FeVariant $feVariant = null
     ): void {
         if ($feVariant) {
             $feVariantsData = $feVariant->getVariantData();
@@ -141,20 +141,7 @@ protected function addVariantsOfVariant(BeVariant $variant, int $level): void
 
     protected function addBeVariant(BeVariant $variant, int $level): void
     {
-        $variantInner = $variant;
-        for ($count = $level; $count > 0; $count--) {
-            if ($count > 1) {
-                $variantInner = $variantInner->getParentBeVariant();
-            } else {
-                $cartProduct = $variantInner->getProduct();
-            }
-        }
-        unset($variantInner);
-
-        if (!isset($cartProduct)) {
-            // ToDo Add Error Message
-            return;
-        }
+        $cartProduct = $variant->getProduct();
 
         $orderProduct = GeneralUtility::makeInstance(
             \Extcode\Cart\Domain\Model\Order\Product::class
@@ -193,11 +180,7 @@ protected function addBeVariant(BeVariant $variant, int $level): void
 
             $orderProduct->addProductAdditional($orderProductAdditional);
 
-            if ($count > 1) {
-                $variantInner = $variantInner->getParentBeVariant();
-            } else {
-                $cartProduct = $variantInner->getProduct();
-            }
+            $variantInner = $variantInner->getParent();
         }
         unset($variantInner);
 
diff --git a/Classes/Service/TaxClassService.php b/Classes/Service/TaxClassService.php
index 3a54beac..d44279d4 100644
--- a/Classes/Service/TaxClassService.php
+++ b/Classes/Service/TaxClassService.php
@@ -33,7 +33,7 @@ public function __construct(
     /**
      * @return TaxClass[]
      */
-    public function getTaxClasses(string $countryCode = null): array
+    public function getTaxClasses(?string $countryCode = null): array
     {
         $taxClasses = [];
         $taxClassSettings = $this->settings['taxClasses'];
diff --git a/Classes/Service/TaxClassServiceInterface.php b/Classes/Service/TaxClassServiceInterface.php
index e1c20143..beb280c6 100644
--- a/Classes/Service/TaxClassServiceInterface.php
+++ b/Classes/Service/TaxClassServiceInterface.php
@@ -18,5 +18,5 @@ interface TaxClassServiceInterface
     /**
      * @return TaxClass[]
      */
-    public function getTaxClasses(string $countryCode = null): array;
+    public function getTaxClasses(?string $countryCode = null): array;
 }
diff --git a/Classes/ViewHelpers/FieldNameViewHelper.php b/Classes/ViewHelpers/FieldNameViewHelper.php
index 6e2475bd..b4593272 100644
--- a/Classes/ViewHelpers/FieldNameViewHelper.php
+++ b/Classes/ViewHelpers/FieldNameViewHelper.php
@@ -55,11 +55,12 @@ protected function getVariantFieldName(BeVariant $variant): string
     {
         $fieldName = '';
 
-        if ($variant->getParentBeVariant()) {
-            $fieldName .= $this->getVariantFieldName($variant->getParentBeVariant());
+        if ($variant->getParent() instanceof BeVariant) {
+            $fieldName .= $this->getVariantFieldName($variant->getParent());
         }
-        if ($variant->getProduct()) {
-            $fieldName .= '[' . $variant->getProduct()->getId() . ']';
+
+        if ($variant->getParent() instanceof Product) {
+            $fieldName .= '[' . $variant->getParent()->getId() . ']';
         }
 
         $fieldName .= '[' . $variant->getId() . ']';
diff --git a/Documentation/Changelog/10.0/Breaking-611-ChangePhpDependency.rst b/Documentation/Changelog/10.0/Breaking-611-ChangePhpDependency.rst
new file mode 100644
index 00000000..eea1c0db
--- /dev/null
+++ b/Documentation/Changelog/10.0/Breaking-611-ChangePhpDependency.rst
@@ -0,0 +1,33 @@
+.. include:: ../../Includes.rst.txt
+
+=================================================
+Breaking: #611 - Change BeVariant Parent Handling
+=================================================
+
+See `Issue 611 <https://github.com/extcode/cart/issues/611>`__
+
+Description
+===========
+
+Previously, a `BeVariant` had either another `BeVariant` or a `Product` as its parent element. These were passed in the
+constructor method.
+
+Thanks to PHP's union types, this can now be resolved. A `BeVariant` now has a `$parent` that is either of type
+`BeVariant` or of type `Product`.
+
+The individual methods have been adapted accordingly and it is checked of which class `$parent` is an instance. In some
+cases, the case differentiation could be omitted completely.
+
+Affected Installations
+======================
+
+All product extensions that use their own `BeVariant` in the products are affected. The provided extensions
+extcode/cart-products and extcode/cart-events will be adapted accordingly.
+
+Migration
+=========
+
+If a custom product extension is used, the constructor must be adapted accordingly. Furthermore, a few
+methods in `BeVariant` have been replaced or their behavior adapted.
+
+.. index:: API
diff --git a/Documentation/Changelog/10.0/Index.rst b/Documentation/Changelog/10.0/Index.rst
new file mode 100644
index 00000000..f1afa74d
--- /dev/null
+++ b/Documentation/Changelog/10.0/Index.rst
@@ -0,0 +1,20 @@
+.. include:: ../../Includes.rst.txt
+
+10.0 Changes
+============
+
+**Table of contents**
+
+.. contents::
+   :local:
+   :depth: 1
+
+Breaking
+--------
+
+.. toctree::
+   :maxdepth: 1
+   :titlesonly:
+   :glob:
+
+   Breaking-*
diff --git a/Documentation/Changelog/9.3/Breaking-611-ChangePhpDependency.rst b/Documentation/Changelog/9.3/Breaking-611-ChangePhpDependency.rst
new file mode 100644
index 00000000..fb7896f0
--- /dev/null
+++ b/Documentation/Changelog/9.3/Breaking-611-ChangePhpDependency.rst
@@ -0,0 +1,30 @@
+.. include:: ../../Includes.rst.txt
+
+======================================
+Breaking: #611 - Change PHP Dependency
+======================================
+
+See `Issue 611 <https://github.com/extcode/cart/issues/611>`__
+
+Description
+===========
+
+Tests with newer versions of phpstan under newer php versions showed that the
+constructor method `\Extcode\Cart\Domain\Model\Cart\BeVariant::__construct()` uses
+required method parameters after optional parameters. This is deprecated since.
+PHP 8.0. (see https://php.watch/versions/8.0/deprecate-required-param-after-optional)
+
+As this may lead to an error in a later PHP version, compatibility is restricted
+to PHP 8.1-8.4.
+
+Affected Installations
+======================
+
+All installations.
+
+Migration
+=========
+
+This restriction currently has no effect. No migration is necessary.
+
+.. index:: API
diff --git a/Documentation/Changelog/9.3/Index.rst b/Documentation/Changelog/9.3/Index.rst
new file mode 100644
index 00000000..5c3b1691
--- /dev/null
+++ b/Documentation/Changelog/9.3/Index.rst
@@ -0,0 +1,20 @@
+.. include:: ../../Includes.rst.txt
+
+9.3 Changes
+===========
+
+**Table of contents**
+
+.. contents::
+   :local:
+   :depth: 1
+
+Breaking
+--------
+
+.. toctree::
+   :maxdepth: 1
+   :titlesonly:
+   :glob:
+
+   Breaking-*
diff --git a/Documentation/Changelog/Index.rst b/Documentation/Changelog/Index.rst
index 256f5ffe..93a2c69a 100644
--- a/Documentation/Changelog/Index.rst
+++ b/Documentation/Changelog/Index.rst
@@ -10,6 +10,8 @@ ChangeLog
    :maxdepth: 5
    :titlesonly:
 
+   10.0/Index
+   9.3/Index
    9.1/Index
    9.0/Index
    8.5/Index
diff --git a/Documentation/guides.xml b/Documentation/guides.xml
index ad995743..39dfb9f7 100644
--- a/Documentation/guides.xml
+++ b/Documentation/guides.xml
@@ -11,8 +11,8 @@
                interlink-shortcode="extcode/cart"
     />
     <project title="Cart"
-             release="9.1.0"
-             version="9.1"
+             release="10.0.0"
+             version="10.0"
              copyright="2018 - 2024"
     />
     <inventory id="t3tsref" url="https://docs.typo3.org/typo3cms/TyposcriptReference/"/>
diff --git a/README.md b/README.md
index be5b4ec6..16823602 100644
--- a/README.md
+++ b/README.md
@@ -50,8 +50,8 @@ Sometimes minor versions also result in minor adjustments to own templates or co
 
 | Cart   | TYPO3      | PHP       | Support/Development                  |
 |--------|------------|-----------|--------------------------------------|
-| 10.x.x | 13.0       | 8.2+      | Features, Bugfixes, Security Updates |
-| 9.x.x  | 12.4       | 8.1+      | Bugfixes, Security Updates           |
+| 10.x.x | 13.4       | 8.2 - 8.4 | Features, Bugfixes, Security Updates |
+| 9.x.x  | 12.4       | 8.1 - 8.4 | Bugfixes, Security Updates           |
 | 8.x.x  | 10.4, 11.5 | 7.2+      | Security Updates                     |
 | 7.x.x  | 10.4       | 7.2 - 7.4 |                                      |
 | 6.x.x  | 9.5        | 7.2 - 7.4 |                                      |
diff --git a/Tests/Unit/Domain/Model/Cart/BeVariantTest.php b/Tests/Unit/Domain/Model/Cart/BeVariantTest.php
index dd255dde..70734a85 100644
--- a/Tests/Unit/Domain/Model/Cart/BeVariantTest.php
+++ b/Tests/Unit/Domain/Model/Cart/BeVariantTest.php
@@ -68,7 +68,6 @@ public function setUp(): void
         $this->beVariant = new BeVariant(
             $this->id,
             $this->product,
-            null,
             $this->title,
             $this->sku,
             $this->priceCalcMethod,
@@ -181,40 +180,6 @@ public function getQuantityReturnsQuantitySetByConstructor(): void
         );
     }
 
-    #[Test]
-    public function constructVariantWithoutCartProductOrVariantThrowsInvalidArgumentException(): void
-    {
-        $this->expectException(\InvalidArgumentException::class);
-
-        new BeVariant(
-            $this->id,
-            null,
-            null,
-            $this->sku,
-            $this->title,
-            $this->priceCalcMethod,
-            $this->price,
-            $this->quantity
-        );
-    }
-
-    #[Test]
-    public function constructVariantWithCartProductAndVariantThrowsInvalidArgumentException(): void
-    {
-        $this->expectException(\InvalidArgumentException::class);
-
-        new BeVariant(
-            $this->id,
-            $this->product,
-            $this->beVariant,
-            $this->sku,
-            $this->title,
-            $this->priceCalcMethod,
-            $this->price,
-            $this->quantity
-        );
-    }
-
     #[Test]
     public function constructWithoutTitleThrowsException(): void
     {
@@ -224,7 +189,6 @@ public function constructWithoutTitleThrowsException(): void
             1,
             $this->product,
             null,
-            null,
             'test-variant-sku',
             0,
             1.0,
@@ -240,7 +204,6 @@ public function constructWithoutSkuThrowsException(): void
         new BeVariant(
             1,
             $this->product,
-            null,
             'Test Variant',
             null,
             0,
@@ -257,7 +220,6 @@ public function constructWithoutQuantityThrowsException(): void
         new BeVariant(
             1,
             $this->product,
-            null,
             'Test Variant',
             'test-variant-sku',
             0,
@@ -448,7 +410,6 @@ public function getParentPriceRespectsTheQuantityDiscountsOfProductsForEachVaria
         $beVariant1 = new BeVariant(
             '1',
             $this->product,
-            null,
             $title,
             $sku,
             $priceCalcMethod,
@@ -460,7 +421,6 @@ public function getParentPriceRespectsTheQuantityDiscountsOfProductsForEachVaria
         $beVariant2 = new BeVariant(
             '2',
             $this->product,
-            null,
             $title,
             $sku,
             $priceCalcMethod,
@@ -472,7 +432,6 @@ public function getParentPriceRespectsTheQuantityDiscountsOfProductsForEachVaria
         $beVariant3 = new BeVariant(
             '3',
             $this->product,
-            null,
             $title,
             $sku,
             $priceCalcMethod,
diff --git a/Tests/Unit/Service/AbstractConfigurationFromTypoScriptServiceTest.php b/Tests/Unit/Service/AbstractConfigurationFromTypoScriptServiceTest.php
index 8b92cf09..25a0c5eb 100644
--- a/Tests/Unit/Service/AbstractConfigurationFromTypoScriptServiceTest.php
+++ b/Tests/Unit/Service/AbstractConfigurationFromTypoScriptServiceTest.php
@@ -180,7 +180,7 @@ public function getTypeZonePluginSettingsReturnsTypeZoneSettings(): void
 
     private function createSubject(array $configurations)
     {
-        $configurationManager = $this->createStub(ConfigurationManagerInterface::class);
+        $configurationManager = self::createStub(ConfigurationManagerInterface::class);
         $configurationManager->method('getConfiguration')->willReturn($configurations);
 
         return new class ($configurationManager, new ServiceFactory()) extends AbstractConfigurationFromTypoScriptService {};
diff --git a/Tests/Unit/Service/TaxClassServiceTest.php b/Tests/Unit/Service/TaxClassServiceTest.php
index 1b9bcf48..80996f99 100644
--- a/Tests/Unit/Service/TaxClassServiceTest.php
+++ b/Tests/Unit/Service/TaxClassServiceTest.php
@@ -243,13 +243,13 @@ public function parsingTaxClassesFromTypoScriptWithIntegerZeroAsCalcIsValid(): v
 
     private function createSubject(array $settings): TaxClassService
     {
-        $configurationManager = $this->createStub(ConfigurationManagerInterface::class);
+        $configurationManager = self::createStub(ConfigurationManagerInterface::class);
         $configurationManager->method('getConfiguration')->willReturn($settings);
 
         return new TaxClassService(
             $configurationManager,
             new TaxClassFactory(
-                $this->createStub(LoggerInterface::class)
+                self::createStub(LoggerInterface::class)
             )
         );
     }
diff --git a/composer.json b/composer.json
index e1148762..8c5a6533 100644
--- a/composer.json
+++ b/composer.json
@@ -48,7 +48,7 @@
         }
     },
     "require": {
-        "php": "^8.2",
+        "php": "~8.2.0 || ~8.3.0 || ~8.4.0",
         "ext-json": "*",
         "ext-openssl": "*",
         "typo3/cms-core": "^13.4",
diff --git a/ext_emconf.php b/ext_emconf.php
index c6c27ed7..a82622c2 100644
--- a/ext_emconf.php
+++ b/ext_emconf.php
@@ -11,7 +11,10 @@
     'author_company' => 'extco.de UG (haftungsbeschränkt)',
     'constraints' => [
         'depends' => [
+            'php' => '8.1.0-8.4.99',
             'typo3' => '13.4.0-13.4.99',
+            'extbase' => '13.4.0-13.4.99',
+            'fluid' => '13.4.0-13.4.99',
         ],
         'conflicts' => [],
         'suggests' => [],
diff --git a/rector.php b/rector.php
index 54b60925..2c72b1d6 100644
--- a/rector.php
+++ b/rector.php
@@ -40,7 +40,7 @@
         ConvertImplicitVariablesToExplicitGlobalsRector::class,
     ])
     ->withConfiguredRule(ExtEmConfRector::class, [
-        ExtEmConfRector::PHP_VERSION_CONSTRAINT => '8.2.0-8.3.99',
+        ExtEmConfRector::PHP_VERSION_CONSTRAINT => '8.2.0-8.4.99',
         ExtEmConfRector::TYPO3_VERSION_CONSTRAINT => '13.4.0-13.4.99',
         ExtEmConfRector::ADDITIONAL_VALUES_TO_BE_REMOVED => [],
     ])