Fatal error: Uncaught Error: Interface "TYPO3\CMS\Core\SingletonInterface" not found in /home/cmsshareacopy/public_html/TYPO3/vendor/typo3/cms-core/Classes/Package/PackageManager.php:51 Stack trace: #0 {main} thrown in /home/cmsshareacopy/public_html/TYPO3/vendor/typo3/cms-core/Classes/Package/PackageManager.php on line 51