Fatal error: Uncaught Error: Class "ApiPlatform\Serializer\AbstractItemNormalizer" not found in /var/www/crm_killing_ninja/vendor/api-platform/core/src/JsonApi/Serializer/ItemNormalizer.php:49 Stack trace: #0 {main} thrown in /var/www/crm_killing_ninja/vendor/api-platform/core/src/JsonApi/Serializer/ItemNormalizer.php on line 49