Fatal error: Uncaught Error: Class 'Symfony\Component\Validator\ConstraintValidator' not found in C:\xampp\htdocs\plugins\Symfony\Component\Validator\Constraints\LuhnValidator.php:31 Stack trace: #0 {main} thrown in C:\xampp\htdocs\plugins\Symfony\Component\Validator\Constraints\LuhnValidator.php on line 31