Fatal error: Uncaught Error: Interface "TYPO3\CMS\Core\SingletonInterface" not found in /var/www/html/dev.hallescherfc.de/vendor/friendsoftypo3/content-blocks/Classes/Schema/SimpleTcaSchemaFactory.php:28 Stack trace: #0 {main} thrown in /var/www/html/dev.hallescherfc.de/vendor/friendsoftypo3/content-blocks/Classes/Schema/SimpleTcaSchemaFactory.php on line 28