Fatal error: Uncaught Error: Class "TYPO3Fluid\Fluid\Core\ViewHelper\AbstractTagBasedViewHelper" not found in /var/www/html/dev.hallescherfc.de/vendor/typo3/cms-backend/Classes/ViewHelpers/ThumbnailViewHelper.php:64 Stack trace: #0 {main} thrown in /var/www/html/dev.hallescherfc.de/vendor/typo3/cms-backend/Classes/ViewHelpers/ThumbnailViewHelper.php on line 64