I have the same problem.
1 SOGO server with a shared calander.
When i make a event in de shared calander with time then i get the error.
--- BEGIN DEBUG INFO ---
Account name: nike @ anjo sogo
Authority: org.dmfs.tasks
LOCAL RESOURCE:
LocalTask=[eTag=null, fileName=76d23e9f-ca05-4956-9c42-51f12599365f.ics, flags=0, id=1, task=Task=[classification=null, color=null, completedAt=null, createdAt=1531077792643, description=null, dtStart=null, due=null, duration=null, exDates=[], geoPosition=null, lastModified=1531077792643, location=null, organizer=null, percentComplete=null, priority=0, rDates=[], rRule=null, status=STATUS:NEEDS-ACTION, summary=Test3, url=null, sequence=0, uid=76d23e9f-ca05-4956-9c42-51f12599365f, shadow$_klass_=class at.bitfire.ical4android.Task, shadow$_monitor_=0], taskList=at.bitfire.davdroid.resource.LocalTaskList@4cdb1c8, shadow$_klass_=class at.bitfire.davdroid.resource.LocalTask, shadow$_monitor_=0]
REMOTE RESOURCE:
https://XXX/SOGo/dav/nike@XXX/Calendar/23F-5B22AA80-1-17769D80/76d23e9f-ca05-4956-9c42-51f12599365f.ics
EXCEPTION:
java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.Calendar.setTimeZone(java.util.TimeZone)' on a null object reference
at java.text.DateFormat.setTimeZone(DateFormat.java:690)
at net.fortuna.ical4j.model.Iso8601.<init>(Iso8601.java:77)
at net.fortuna.ical4j.model.Iso8601.<init>(Iso8601.java:94)
at net.fortuna.ical4j.model.Date.<init>(Date.java:130)
at net.fortuna.ical4j.model.DateTime.<init>(DateTime.java:235)
at net.fortuna.ical4j.model.DateTime.<init>(DateTime.java:244)
at net.fortuna.ical4j.model.property.UtcProperty.<init>(UtcProperty.java:67)
at net.fortuna.ical4j.model.property.DtStamp.<init>(DtStamp.java:94)
at net.fortuna.ical4j.model.component.VToDo.<init>(VToDo.java:149)
at net.fortuna.ical4j.model.component.VToDo.<init>(VToDo.java:143)
at at.bitfire.ical4android.Task.write(Task.kt:133)
at at.bitfire.davdroid.syncadapter.TasksSyncManager$prepareUpload$1.invoke(TasksSyncManager.kt:83)
at at.bitfire.davdroid.syncadapter.TasksSyncManager$prepareUpload$1.invoke(TasksSyncManager.kt:42)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager.useLocal(BaseDavSyncManager.kt:296)
at at.bitfire.davdroid.syncadapter.TasksSyncManager.prepareUpload(TasksSyncManager.kt:78)
at at.bitfire.davdroid.syncadapter.TasksSyncManager.prepareUpload(TasksSyncManager.kt:42)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager$uploadDirty$1$1.invoke(BaseDavSyncManager.kt:142)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager$uploadDirty$1$1.invoke(BaseDavSyncManager.kt:37)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager.useRemote(BaseDavSyncManager.kt:303)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager$uploadDirty$1.invoke(BaseDavSyncManager.kt:140)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager$uploadDirty$1.invoke(BaseDavSyncManager.kt:37)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager.useLocal(BaseDavSyncManager.kt:296)
at at.bitfire.davdroid.syncadapter.BaseDavSyncManager.uploadDirty(BaseDavSyncManager.kt:131)
at at.bitfire.davdroid.syncadapter.SyncManager.performSync(SyncManager.kt:109)
at at.bitfire.davdroid.syncadapter.TasksSyncAdapterService$TasksSyncAdapter.sync(TasksSyncAdapterService.kt:64)
at at.bitfire.davdroid.syncadapter.SyncAdapterService$SyncAdapter.onPerformSync(SyncAdapterService.kt:97)
at android.content.AbstractThreadedSyncAdapter$SyncThread.run(AbstractThreadedSyncAdapter.java:272)
SOFTWARE INFORMATION
Package: at.bitfire.davdroid
Version: 1.11.5-gplay (233) from 17 jun. 2018
Installed from: com.android.vending
JB Workaround installed: no
CONNECTIVITY (at the moment)
Active connection: WiFi, CONNECTED
CONFIGURATION
Power saving disabled: no
android.permission.READ_CONTACTS permission: granted
android.permission.WRITE_CONTACTS permission: granted
android.permission.READ_CALENDAR permission: granted
android.permission.WRITE_CALENDAR permission: granted
org.dmfs.permission.READ_TASKS permission: granted
org.dmfs.permission.WRITE_TASKS permission: granted
System-wide synchronization: automatically
Account: nike @ anjo sogo
Address book sync. interval: 240 min
Calendar sync. interval: 15 min
OpenTasks sync. interval: 240 min
WiFi only: false
[CardDAV] Contact group method: GROUP_VCARDS
[CalDAV] Time range (past days): 90
Manage calendar colors: false
SQLITE DUMP
android_metadata
| locale |
| nl_NL |
----------
services
| _id | accountName | service | principal |
| 2 | nike @ anjo sogo | carddav | https://XXX.com/SOGo/dav/nike@XXX/ |
| 3 | nike @ anjo sogo | caldav | https://XXXl.com/SOGo/dav/nike@XXX/ |
----------
sqlite_sequence
| name | seq |
| services | 3 |
| homesets | 4 |
| collections | 10 |
----------
homesets
| _id | serviceID | url |
| 3 | 2 | https://XXX.com/SOGo/dav/nike@XXX/Contacts/ |
| 4 | 3 | https://XXX.com/SOGo/dav/nike@XXX.com/Calendar/ |
----------
collections
| _id | serviceID | type | url | readOnly | forceReadOnly | displayName | description | color | timezone | supportsVEVENT | supportsVTODO | source | sync |
| 7 | 2 | ADDRESS_BOOK | https://XXX.com/SOGo/dav/nike@XXX.com/Contacts/personal/ | 0 | 0 | Persoonlijk adresboek | <null> | <null> | <null> | 0 | 0 | <null> | 0 |
| 8 | 2 | ADDRESS_BOOK | https://XXX.com/SOGo/dav/nike@XXX.com/Contacts/users/ | 0 | 0 | Domain Address Book | <null> | <null> | <null> | 0 | 0 | <null> | 0 |
| 9 | 3 | CALENDAR | https://XXX.com/SOGo/dav/nike@XXX.com/Calendar/personal/ | 0 | 0 | Persoonlijke agenda | <null> | -5592406 | <null> | 1 | 1 | <null> | 0 |
| 10 | 3 | CALENDAR | https://XXX.com/SOGo/dav/nike@XXX.com/Calendar/23F-5B22AA80-1-17769D80/ | 0 | 0 | Rene & Anjo | <null> | -5592406 | <null> | 1 | 1 | <null> | 1 |
----------
SYSTEM INFORMATION
Android version: 8.0.0 (R16NW.G930FXXU2EREM)
Device: samsung SM-G930F (herolte)
--- END DEBUG INFO ---
I removed my domain.
I have a samsung galaxy S7 with android 8.0.0