Fatal error: Uncaught Error: Class "Symfony\Component\Validator\ConstraintValidator" not found in D:\xampp\htdocs\pimcore\my-project\vendor\symfony\validator\Constraints\IsNullValidator.php:21 Stack trace: #0 {main} thrown in D:\xampp\htdocs\pimcore\my-project\vendor\symfony\validator\Constraints\IsNullValidator.php on line 21