[kronolith] Call to a member function dateString() on null

[Ferdinand Gruber]

Today I get an error from kronolith on my server:

Here is the full message from systemd. This message appears every time 
the Android Davx5 app tries to synchronize.

Broadcast message from systemd-journald at t2792 (Tue 2020-09-22 14:24:39 
CEST):

HORDE[19373]: [kronolith] Error: Call to a member function dateString() 
on null in /srv/www/htdocs/horde/kronolith/lib/Kronolith.php:444
Stack trace:
#0 /srv/www/htdocs/horde/kronolith/lib/Driver/Sql.php(312): 
Kronolith::addEvents(Array, Object(Kronolith_Event_Sql), NULL, NULL, 
false, false, false)
#1 /srv/www/htdocs/horde/kronolith/lib/Driver.php(310): 
Kronolith_Driver_Sql->_listEvents(NULL, NULL, Array)
#2 /srv/www/htdocs/horde/kronolith/lib/Application.php(743): 
Kronolith_Driver->listEvents(NULL, NULL, Array)
#3 /usr/share/php7/PEAR/Horde/Registry.php(1197): 
Kronolith_Application->davGetObjects('calendar:fkDvuF...')
#4 /usr/share/php7/PEAR/Horde/Dav/Calendar/Backend.php(138): 
Horde_Registry->callAppMethod('kronolith', 'davGetObjects', Array)
#5 /usr/share/php7/PEAR/Sabre/CalDAV/Backend/AbstractBackend.php(113): 
Horde_Dav_Calendar_Backend->getCalendarObjects('calendar:fkDvuF...')
#6 /usr/share/php7/PEAR/Sabre/CalDAV/Calendar.php(372): 
Sabre\CalDAV\Backend\AbstractBackend->calendarQuery('calendar:fkDvuF...', 
Array)
#7 /usr/share/php7/PEAR/Sabre/CalDAV/Plugin.php(591): 
Sabre\CalDAV\Calendar->calendarQuery(Array)
#8 /usr/share/php7/PEAR/Sabre/CalDAV/Plugin.php(265): 
Sabre\CalDAV\Plugin->calendarQueryReport(Object(DOMDocument))
#9 [internal function]: 
Sabre\CalDAV\Plugin->report('{urn:ietf:param...', Object(DOMDocument), 
'calendars/ferdi...')
#10 /usr/share/php7/PEAR/Sabre/DAV/Server.php(433): 
call_user_func_array(Array, Array)
#11 /usr/share/php7/PEAR/Sabre/DAV/Server.php(1066): 
Sabre\DAV\Server->broadcastEvent('report', Array)
#12 [internal function]: Sabre\DAV\Server->httpReport('calendars/ferdi...')
#13 /usr/share/php7/PEAR/Sabre/DAV/Server.php(474): 
call_user_func(Array, 'calendars/ferdi...')
#14 /usr/share/php7/PEAR/Sabre/DAV/Server.php(214): 
Sabre\DAV\Server->invokeMethod('REPORT', 'calendars/ferdi...')
#15 /usr/share/php7/PEAR/Horde/Rpc/Webdav.php(66): Sabre\DAV\Server->exec()
#16 /srv/www/htdocs/horde/rpc.php(160): Horde_Rpc_Webdav->getResponse('')
#17 {main} [pid 19373 on line 74 of 
"/usr/share/php7/PEAR/Horde/ErrorHandler.php"]

Broadcast message from systemd-journald at t2792 (Tue 2020-09-22 14:24:41 
CEST):

HORDE[19373]: [kronolith] Allowed memory size of 268435456 bytes 
exhausted (tried to allocate 182456320 bytes) [pid 19373 on line 130 of 
"/usr/share/php7/PEAR/Horde/ErrorHandler.php"]

The Android Sync-app DAVX5 also shows an error message: Expected 207 
Multi-Status got 200 OK

Is there something wrong with a data record in kronolith-events? How can 
I debug this?

Horde on my server is up to date.

Please help

-- 
Regards from Austria
Ferdinand Gruber