Fatal error: Uncaught Error: Interface "OCA\Mail\Service\Group\IGroupService" not found in /home/tzuovhm/tzuovhm/apps_/mail/lib/Service/Group/ContactsGroupService.php:15 Stack trace: #0 {main} thrown in /home/tzuovhm/tzuovhm/apps_/mail/lib/Service/Group/ContactsGroupService.php on line 15