Fatal error: Uncaught Error: Class 'Symfony\Component\Workflow\Event\Event' not found in C:\xampp\htdocs\plugins\Symfony\Component\Workflow\Event\CompletedEvent.php:18 Stack trace: #0 {main} thrown in C:\xampp\htdocs\plugins\Symfony\Component\Workflow\Event\CompletedEvent.php on line 18