Fatal error: Uncaught Error: Interface 'Sabre\DAV\PropertyStorage\Backend\BackendInterface' not found in /home/malert/WebDAV/vendor/sabre/dav/tests/Sabre/DAV/PropertyStorage/Backend/Mock.php:8 Stack trace: #0 {main} thrown in /home/malert/WebDAV/vendor/sabre/dav/tests/Sabre/DAV/PropertyStorage/Backend/Mock.php on line 8