Hier der Output aus dem Apache Log (Loglevel debug) eines fehlerhaften Aufrufs:
[Sat Dec 22 11:39:01.458625 2018] [:error] [pid 18140] [client 1.1.1.1:50487] PHP Warning: array_intersect(): Argument #2 is not an array in /usr/share/egroupware/calendar/inc/class.calendar_groupdav.inc.php on line 818, referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458694 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #1 /usr/share/egroupware/calendar/inc/class.calendar_groupdav.inc.php(818): array_intersect(Array, NULL), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458704 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #2 /usr/share/egroupware/calendar/inc/class.calendar_groupdav.inc.php(800): calendar_groupdav::isParticipant(Array, -7), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458713 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #3 /usr/share/egroupware/calendar/inc/class.calendar_groupdav.inc.php(691): calendar_groupdav::get_series('calendar-5031-3...', Object(calendar_boupdate), false, -7), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458722 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #4 /usr/share/egroupware/calendar/inc/class.calendar_groupdav.inc.php(644): calendar_groupdav->iCal(Array, -7, NULL), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458731 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #5 /usr/share/egroupware/api/src/CalDAV.php(996): calendar_groupdav->get(Array, '6885.ics', -7), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458740 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #6 /usr/share/egroupware/api/src/WebDAV/Server.php(1278): EGroupware\\Api\\CalDAV->GET(Array), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458749 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #7 /usr/share/egroupware/api/src/WebDAV/Server.php(306): HTTP_WebDAV_Server->http_GET(), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458758 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #8 /usr/share/egroupware/api/src/CalDAV.php(2058): HTTP_WebDAV_Server->ServeRequest(NULL), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/
[Sat Dec 22 11:39:01.458767 2018] [:error] [pid 18140] [client 1.1.1.1:50487] #9 /usr/share/egroupware/groupdav.php(52): EGroupware\\Api\\CalDAV->ServeRequest(), referer: http://neuromancer/egroupware/groupdav.php/familie/calendar/