Moodle Installation 3.5.11+ PHP7.2

Exception - Class 'calendar_event' not found

More information about this error
×Debug info:
Error code: generalexceptionmessage
×Stack trace: * line 693 of /mod/bigbluebuttonbn/lib.php: Error thrown

• line 632 of /mod/bigbluebuttonbn/lib.php: call to bigbluebuttonbn_process_post_save_event()
• line 167 of /mod/bigbluebuttonbn/lib.php: call to bigbluebuttonbn_process_post_save()
• line 575 of /course/modlib.php: call to bigbluebuttonbn_update_instance()
• line 152 of /course/modedit.php: call to update_moduleinfo()
  ×Output buffer: <br /> <b>Warning</b>: Use of undefined constant CALENDAR_EVENT_TYPE_ACTION - assumed 'CALENDAR_EVENT_TYPE_ACTION' (this will throw an Error in a future version of PHP) in <b>/var/www/html/elearn2.apopsi.gr/mod/bigbluebuttonbn/lib.php</b> on line <b>673</b><br />