Fatal error: Uncaught Error: Class 'Symfony\Component\EventDispatcher\Event' not found in /home/edmedu/www/edmeducation.co.kr/tw-dev/vendor/symfony/event-dispatcher/GenericEvent.php:21 Stack trace: #0 {main} thrown in /home/edmedu/www/edmeducation.co.kr/tw-dev/vendor/symfony/event-dispatcher/GenericEvent.php on line 21