Fatal error: Uncaught Error: Class 'Symfony\Component\EventDispatcher\Event' not found in /home/eberhardschwarze/public_html/vendor/contao/core-bundle/src/Event/ImageSizesEvent.php:22 Stack trace: #0 {main} thrown in /home/eberhardschwarze/public_html/vendor/contao/core-bundle/src/Event/ImageSizesEvent.php on line 22