Fatal error: Uncaught Error: Class 'Symfony\Component\Validator\ConstraintValidator' not found in /home/coelhost/staging.cls.pt/storage-oc3020/vendor/symfony/validator/Constraints/IsbnValidator.php:28 Stack trace: #0 {main} thrown in /home/coelhost/staging.cls.pt/storage-oc3020/vendor/symfony/validator/Constraints/IsbnValidator.php on line 28