Fatal error: Uncaught Error: Class "OCP\AppFramework\Controller" not found in /users/ms-it/www/oc/apps-external/files_pdfviewer/lib/Controller/DisplayController.php:19 Stack trace: #0 {main} thrown in /users/ms-it/www/oc/apps-external/files_pdfviewer/lib/Controller/DisplayController.php on line 19