Fatal error: Uncaught Error: Interface 'Sabre\DAVACL\IPrincipal' not found in /home/malert/WebDAV/vendor/sabre/dav/lib/CalDAV/Principal/IProxyWrite.php:17 Stack trace: #0 {main} thrown in /home/malert/WebDAV/vendor/sabre/dav/lib/CalDAV/Principal/IProxyWrite.php on line 17