Fatal error: Uncaught Error: Class "Symfony\Component\EventDispatcher\Event" not found in /home/rankting/public_html/ALT/ranketing.de (contao)/vendor/contao/core-bundle/src/Event/PreviewUrlConvertEvent.php:20 Stack trace: #0 {main} thrown in /home/rankting/public_html/ALT/ranketing.de (contao)/vendor/contao/core-bundle/src/Event/PreviewUrlConvertEvent.php on line 20