Error of sync for a several users - Glpi + Caldav Sync

[etiennem30]

Hello Sabre people.
I'm a GLPI user with the Caldav Synchronizer tool.

For most of my users, the caldav sync works well.
I've several users where sync works partially or not at all.

The general error is the following one :

` CalDavSynchronizer.DataAccess.WebDavClientException: Response status code does not indicate success: '500' ('Internal Server Error'). Message:

<d:error xmlns:d="DAV:" xmlns:s=http://sabredav.org/ns>
<s:sabredav-version>4.1.3</s:sabredav-version>
<s:exception>Sabre\VObject\EofException</s:exception>
<s:message>End of document reached prematurely</s:message>
</d:error>`

Below this error, into caldavsync report, i've following trace
` at CalDavSynchronizer.DataAccess.HttpClientBasedClient.WebDavClient.d__10.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at CalDavSynchronizer.DataAccess.HttpClientBasedClient.WebDavClient.d__9.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at CalDavSynchronizer.DataAccess.HttpClientBasedClient.WebDavClient.d__7.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at CalDavSynchronizer.DataAccess.CalDavDataAccess.d__29.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at CalDavSynchronizer.DataAccess.CalDavDataAccess.d__29.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at CalDavSynchronizer.Implementation.CalDavRepository`1.d__9.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at GenSync.EntityRepositories.VersionAwareToStateAwareEntityRepositoryAdapter`4.d__5.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at GenSync.Synchronization.Synchronizer`11.d__27.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at GenSync.Synchronization.ContextCreatingSynchronizerDecorator`7.d__3.MoveNext()

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at CalDavSynchronizer.Scheduling.SynchronizationProfileRunner.d__22.MoveNext()
false
00:00:00.9810826
`

Into phph-errors.log of GLPI, i've following error for most impacted user
[2022-10-17 09:02:46] glpiphplog.ERROR: Glpi\CalDAV\Server::logException() in /opt/glpi-9.5.6/inc/caldav/server.class.php line 97 Sabre\VObject\EofException: End of document reached prematurely #0 /opt/glpi-9.5.6/vendor/sabre/vobject/lib/Parser/MimeDir.php(205): Sabre\VObject\Parser\MimeDir->readLine() #1 /opt/glpi-9.5.6/vendor/sabre/vobject/lib/Parser/MimeDir.php(174): Sabre\VObject\Parser\MimeDir->parseLine('DTEND;TZ') #2 /opt/glpi-9.5.6/vendor/sabre/vobject/lib/Parser/MimeDir.php(90): Sabre\VObject\Parser\MimeDir->parseDocument() #3 /opt/glpi-9.5.6/vendor/sabre/vobject/lib/Reader.php(47): Sabre\VObject\Parser\MimeDir->parse('BEGIN:VCALENDAR...', 0) #4 /opt/glpi-9.5.6/inc/caldav/traits/vobjectconvertertrait.class.php(82): Sabre\VObject\Reader::read('BEGIN:VCALENDAR...') #5 /opt/glpi-9.5.6/inc/planningexternalevent.class.php(436): PlanningExternalEvent->getVCalendarForItem(Object(PlanningExternalEvent), 'VEVENT') #6 /opt/glpi-9.5.6/inc/planningexternalevent.class.php(407): PlanningExternalEvent->getAsVCalendar() #7 /opt/glpi-9.5.6/inc/planningexternalevent.class.php(380): PlanningExternalEvent::getItemsAsVCalendars(Array) #8 /opt/glpi-9.5.6/inc/caldav/backend/calendar.class.php(190): PlanningExternalEvent::getUserItemsAsVCalendars(16) #9 /opt/glpi-9.5.6/vendor/sabre/dav/lib/CalDAV/Backend/AbstractBackend.php(110): Glpi\CalDAV\Backend\Calendar->getCalendarObjects('user_16') #10 /opt/glpi-9.5.6/vendor/sabre/dav/lib/CalDAV/Calendar.php(354): Sabre\CalDAV\Backend\AbstractBackend->calendarQuery('user_16', Array) #11 /opt/glpi-9.5.6/vendor/sabre/dav/lib/CalDAV/Plugin.php(598): Sabre\CalDAV\Calendar->calendarQuery(Array) #12 /opt/glpi-9.5.6/vendor/sabre/dav/lib/CalDAV/Plugin.php(258): Sabre\CalDAV\Plugin->calendarQueryReport(Object(Sabre\CalDAV\Xml\Request\CalendarQueryReport)) #13 /opt/glpi-9.5.6/vendor/sabre/event/lib/WildcardEmitterTrait.php(89): Sabre\CalDAV\Plugin->report('{urn:ietf:param...', Object(Sabre\CalDAV\Xml\Request\CalendarQueryReport), 'calendars/users...') #14 /opt/glpi-9.5.6/vendor/sabre/dav/lib/DAV/CorePlugin.php(685): Sabre\DAV\Server->emit('report', Array) #15 /opt/glpi-9.5.6/vendor/sabre/event/lib/WildcardEmitterTrait.php(89): Sabre\DAV\CorePlugin->httpReport(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response)) #16 /opt/glpi-9.5.6/vendor/sabre/dav/lib/DAV/Server.php(472): Sabre\DAV\Server->emit('method:REPORT', Array) #17 /opt/glpi-9.5.6/vendor/sabre/dav/lib/DAV/Server.php(253): Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response)) #18 /opt/glpi-9.5.6/caldav.php(47): Sabre\DAV\Server->start() #19 {main} {"user":"16@glpiserver"}

I've managed to find some useful info on the web.
For some users, I managed to solve the problem by reducing the recovery period (changed from 10 days in the past + 30 days in the future) because i'm convinced the problem come form recurring meeting and / or old meeting that is not valide anymore.

Any help will be appreciated, because I don't have any other idea to solve this problem.

Thanks in advance for your help.

Etienne