Fatal error: Uncaught Error: Interface "TYPO3\CMS\Backend\Toolbar\ToolbarItemInterface" not found in /var/www/html/dev.hallescherfc.de/vendor/typo3/cms-backend/Classes/Backend/ToolbarItems/UserToolbarItem.php:35 Stack trace: #0 {main} thrown in /var/www/html/dev.hallescherfc.de/vendor/typo3/cms-backend/Classes/Backend/ToolbarItems/UserToolbarItem.php on line 35