Fatal error: Uncaught Error: Class 'Symfony\Component\Validator\ConstraintValidator' not found in /home/discovergreece/public_html/vendor/symfony/validator/Constraints/NotNullValidator.php:21 Stack trace: #0 {main} thrown in /home/discovergreece/public_html/vendor/symfony/validator/Constraints/NotNullValidator.php on line 21