Fatal error: Uncaught Error: Interface "Sabre\Xml\Element" not found in /var/www/apache/dev/cal/web/vendor/sabre/dav/lib/DAV/Xml/Property/Href.php:26 Stack trace: #0 {main} thrown in /var/www/apache/dev/cal/web/vendor/sabre/dav/lib/DAV/Xml/Property/Href.php on line 26