Fatal error: Uncaught Error: Interface "TYPO3\CMS\Core\SingletonInterface" not found in /var/www/html/dev.hallescherfc.de/vendor/nng/nnhelpers/Classes/Utilities/Dom.php:14 Stack trace: #0 {main} thrown in /var/www/html/dev.hallescherfc.de/vendor/nng/nnhelpers/Classes/Utilities/Dom.php on line 14