Hi,
since I received Android 8.0 on my Huawei P10, the following error keeps occuring when synchronizing with my Nextcloud:
--- BEGIN DEBUG INFO ---
SYNCHRONIZATION INFO
Synchronization phase: 4
Account name: Nextcloud
Authority: org.dmfs.tasks
EXCEPTION:
at.bitfire.ical4android.CalendarStorageException: Couldn't read locally stored event
at at.bitfire.ical4android.AndroidTask.getTask(AndroidTask.kt:68)
at at.bitfire.davdroid.resource.LocalTaskList.getDirty(LocalTaskList.kt:122)
at at.bitfire.davdroid.syncadapter.SyncManager.uploadDirty(SyncManager.kt:335)
at at.bitfire.davdroid.syncadapter.SyncManager.performSync(SyncManager.kt:136)
at at.bitfire.davdroid.syncadapter.TasksSyncAdapterService$TasksSyncAdapter.sync(TasksSyncAdapterService.kt:64)
at at.bitfire.davdroid.syncadapter.SyncAdapterService$SyncAdapter.onPerformSync(SyncAdapterService.kt:85)
at android.content.AbstractThreadedSyncAdapter$SyncThread.run(AbstractThreadedSyncAdapter.java:272)
Caused by: 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.Date.<init>(Date.java:150)
at net.fortuna.ical4j.model.DateTime.<init>(DateTime.java:253)
at at.bitfire.ical4android.AndroidTask.populateTask(AndroidTask.kt:131)
at at.bitfire.davdroid.resource.LocalTask.populateTask(LocalTask.kt:47)
at at.bitfire.ical4android.AndroidTask.getTask(AndroidTask.kt:63)
... 6 more
SOFTWARE INFORMATION
Package: at.bitfire.davdroid
Version: 1.10.1.1-gplay (206) from 20.01.2018
Installed from: com.android.vending
JB Workaround installed: no
CONNECTIVITY (at the moment)
Active connection: WiFi, CONNECTED
CONFIGURATION
Power saving disabled: yes
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: Nextcloud
Address book sync. interval: 1440 min
Calendar sync. interval: 60 min
OpenTasks sync. interval: 60 min
WiFi only: false
[CardDAV] Contact group method: GROUP_VCARDS
[CalDAV] Time range (past days): 90
Manage calendar colors: true
Address book account: Kontakte (Nextcloud dA)
Main account: Account {name= XXXXXXXXX, type=bitfire.at.davdroid}
URL: https://xxxxxx.no-ip.org/remote.php/carddav/addressbooks/xxxxxx/Kontakte/
Sync automatically: true
SQLITE DUMP
android_metadata
| locale |
| de_DE |
----------
services
| _id | accountName | service | principal |
| 1 | Nextcloud | carddav | https://xxxxxx.no-ip.org/remote.php/carddav/principals/xxxxxx/ |
| 2 | Nextcloud | caldav | https://xxxxxx.no-ip.org/remote.php/caldav/principals/xxxxxx/ |
----------
sqlite_sequence
| name | seq |
| services | 4 |
| homesets | 11 |
| collections | 57 |
----------
homesets
| _id | serviceID | url |
| 2 | 1 | https://xxxxxx.no-ip.org/remote.php/carddav/addressbooks/xxxxxx/ |
| 11 | 2 | https://xxxxxx.no-ip.org/remote.php/caldav/calendars/xxxxxx/ |
----------
collections
| _id | serviceID | type | url | readOnly | forceReadOnly | displayName | description | color | timezone | supportsVEVENT | supportsVTODO | source | sync |
| 5 | 1 | ADDRESS_BOOK | https://xxxxxx.no-ip.org/remote.php/carddav/addressbooks/xxxxxx/Kontakte/ | 0 | 0 | Kontakte | <null> | <null> | <null> | 0 | 0 | <null> | 1 |
| 52 | 2 | CALENDAR | https://xxxxxx.no-ip.org/remote.php/caldav/calendars/xxxxxx/contact_birthdays/ | 1 | 0 | Geburtstage von Kontakten | <null> | -54 | <null> | 1 | 0 | <null> | 1 |
| 53 | 2 | CALENDAR | https://xxxxxx.no-ip.org/remote.php/caldav/calendars/xxxxxx/familie/ | 0 | 0 | Familie | <null> | -9115730 | <null> | 1 | 1 | <null> | 1 |
| 54 | 2 | CALENDAR | https://xxxxxx.no-ip.org/remote.php/caldav/calendars/xxxxxx/pers%c3%b6nlich/ | 0 | 0 | Persönlich | Persönlich | -16777216 | <null> | 1 | 1 | <null> | 1 |
| 55 | 2 | CALENDAR | https://xxxxxx.no-ip.org/remote.php/caldav/calendars/xxxxxx/xxxx/ | 0 | 0 | TakeASP | <null> | -39936 | <null> | 1 | 1 | <null> | 1 |
| 56 | 2 | CALENDAR | https://xxxxxx.no-ip.org/remote.php/caldav/calendars/xxxxxx/xxxxxxxxxxx/ | 0 | 0 | Team Orange | <null> | -26112 | <null> | 1 | 1 | <null> | 1 |
| 57 | 2 | CALENDAR | https://xxxxxx.no-ip.org/remote.php/caldav/calendars/xxxxxx/xxx/ | 0 | 0 | Vogel Business Media | Vogel Business Media | -16687987 | <null> | 1 | 1 | <null> | 1 |
----------
SYSTEM INFORMATION
Android version: 8.0.0 (VTR-L09 8.0.0.360(C432))
Device: HUAWEI VTR-L09 (HWVTR)
--- END DEBUG INFO ---
This issue doesn’t occur on the same device when I use CalDAV-Sync e.g.
Best regards
Thomas
Is this error reproducible? Can you provide steps to reproduce (including your system time zone and task details)? I’d need to reproduce the problem so that I can have a look at that.
Hello,
Did you already find out which task was related?
For the records: We have received several reports with this exception. However, I was still unable to reproduce this issue and thus have no idea where it might come from…
If you have any useful hints, please let us know.
ical4j report: https://github.com/ical4j/ical4j/issues/229
It happens to me as well, every time it syncs this errors appears as notification.
I have Android 8.0.
@dolohow Unfortunately, we still don’t have an idea what the problem could be or how it could be reproduced. Any hints are appreciated…
Hi,
now i update DavDroid v1.11.1-gplay - and this issue disappear. 
Below you can find the error log, from the previous version.
Maybe 1.11.1 fixes this problem for the others too? We haven’t changed anything about event/calendar handling in .1, but if it’s fixed – even better 
I still have the issue, with davdroid 1.11.1 galaxy S8 android version 8.0.0
Issue 229 on github also mentions another linked issue which is still open but mentions hcalendar:- https://github.com/ical4j/ical4j/issues/219
Mine failed on this Ical entry if useful:-
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//ddaysoftware.com//NONSGML DDay.iCal 1.0//EN
BEGIN:VTIMEZONE
TZID:GMT Standard Time
BEGIN:STANDARD
DTSTART:19701025T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYHOUR=2;BYMINUTE=0;BYMONTH=10
TZNAME:GMT Standard Time
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19700329T010000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYHOUR=1;BYMINUTE=0;BYMONTH=3
TZNAME:GMT Summer Time
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
ATTENDEE;PARTSTAT=NEEDS-ACTION;CN=bob@example.com;ROLE=REQ-PARTICIPANT;RS
VP=TRUE;SCHEDULE-AGENT=CLIENT:mailto:bob@example.com
CLASS:PUBLIC
DESCRIPTION:Call To +445556487078\nNumber: +445556487078\nDuration: 0 secon
ds
DTEND;TZID=GMT Standard Time:20180418T102600
DTSTAMP:20180505T145147Z
DTSTART;TZID=GMT Standard Time:20180418T102600
ORGANIZER;CN=bob@example.com;SCHEDULE-AGENT=CLIENT;SCHEDULE-STATUS=1.1:ma
ilto:bob@example.com
PRIORITY:5
SEQUENCE:0
SUMMARY:Call To +445556487078
TRANSP:OPAQUE
UID:00f49511-ae3e-4d70-bc71-925514936f2f
X-MICROSOFT-CDO-BUSYSTATUS:BUSY
END:VEVENT
END:VCALENDAR
it was working fine syncing with cpanel (horde) as the server and now I have just switched to self hosted davical 1.1.4 the problem has arisen.
OK I fixed my issue by adding a line to the davical config to handle the nonstandard timezone as follows:-
$c->timezone_translations = array( ‘GMT Standard Time’ => ‘Europe/London’ );
Thanks. Couldn’t reproduce this on 8.0 in the emulator… I guess it must be related to time zone name, maybe because of the space? And it seems to occur in very specific images of 8.0.0 only… and it’s an Android bug, because java.text.DateFormat.setTimeZone(DateFormat.java:690) throws the exception, and that’s part of the Android Java library (and not in userspace, i.e. ical4android/DAVdroid)…
I am also having this problem. I just noticed it now, while debugging the fact that new calendar entries were not being synced from the phone to the server. I tried disabling the calendar from the sync settings (which removed all entries from the phone calendar, as expected), and then reenabling the calendar. I now have the same exception above, in one ICS entry. Syncing does not work, I am assuming the exception kills the sync process.
I am attaching the ICS that causes the problem, as retrieved from the ownCloud server following the URL specified in the DAVDroid debug output. For some reason, the dates are all wrong, shifted by multiple decades. There must have been some corruption somewhere along the way, possibly at an earlier time. I hope it did not affect many entries.
@rfc2822 said in NullPointerException: Attempt to invoke virtual method 'void java.util.Calendar.setTimeZone(java.util.TimeZone)' on a null object reference:
Maybe 1.11.1 fixes this problem for the others too? We haven’t changed anything about event/calendar handling in .1, but if it’s fixed – even better
No, I have updated to 1.11.3-gplay and the issue is still there. What’s even worse, I don’t receive a notification about the problem, it just silently stopped syncing.
I’m using Android 8.0.0 and radicale
We received the information from @belidzs that the latest Android update fixed the problem.
I guess this is an Android firmware problem and encourage everyone with this problem to update to the latest firmware version as soon as possible.
Does upgrading Android fix this problem for other affected users here, too?
Hello,
I was getting the same error message until I have checked the Contact birthdays calendar to sync in CalDAV as it was intentionally not set to sync from the very beginning.
Right now, I am not getting that error message again, even despite that I have force closed DAVDroid and reopened it.
Now I cannot even see my calendars anymore 
I am attaching two debug logs and a screenshot.
According to the debug log, the only difference is the sync row 0 vs 1.
Hum, that is interesting… A basic reinstallation of DAVdroid 1.11.3-gplay was not helping, but when I have installed 1.9.9-gplay, the sync worked as expected. Then I’ve installed 1.11.2-gplay and it worked too. Then I have installed 1.11.3-gplay back, and so it has also worked.
I am confused now 
The good point that it is working now for me. (without me cleaning the brute force attempts table, see below)
If you anyone is having the same issue while using Nextcloud or Owncloud, please try cleaning your brute force attempts table from it:
1. stop your nextcloud/owncloud instance;
2. backup your nextcloud/owncloud database;
3. delete records from the brute force attempts table:
$ sqlite3 /path/to/nextcloud/data/owncloud.db
sqlite> BEGIN;
sqlite> SELECT * FROM oc_bruteforce_attempts;
sqlite> DELETE FROM oc_bruteforce_attempts;
sqlite> SELECT * FROM oc_bruteforce_attempts;
sqlite> COMMIT;
sqlite> .quit
4. start your Nextcloud/Owncloud back again and try DAVdroid to sync the Calendar again.
Kind regards,
Andrey Arapov
@arno Thanks for the update. Were there any Android/system updates in this time?
@rfc2822 AFAIR, there was Android OS update quiet some time ago, longer before I started to see the error message. The first time I’ve got the error message was the last week as I was traveling to Greece, so the timezone was shifted by +1 hour. That was the time I started to see the error message. Also, it might be worth mentioning, I was making a phone factory reset just a day before I traveled to Greece last week.
I had the same exception all of a sudden this afternoon. I updated DAVdroid to 1.11.4-beta4-ose (from F-Droid) yesterday evening, syncing flawlessly during the entire morning. Disabling and enabling claendars in DAVdroid didn’t make any difference. I also deleted the calendar storage data from the Android settings > apps, same error occurred.
Hum, that is interesting… A basic reinstallation of DAVdroid
1.11.3-gplaywas not helping, but when I have installed1.9.9-gplay, the sync worked as expected. Then I’ve installed1.11.2-gplayand it worked too. Then I have installed1.11.3-gplayback, and so it has also worked.
That’s basically what seems to have helped also for me: I uninstalled DAVdroid 1.11.1-ose (the oldest version F-Droid is offering) and synced my calendars. Then I updated to 1.11.2-ose and synced, no problem occurred. Finally I updated to 1.11.4-beta4-ose and up until now sync works like a charm.
I hope this help aniling the culprit down.
I’m also experiencing this bug for the last few days. No major update of Android for the last few weeks.
I noticed this bug was triggered when I created/updated an event on my calendar (stored on a private Owncloud).
Is there a way to detect which event could have triggered the bug?
@dco The issue resolved by itself. No Android update, no Owncloud update, just moved some calendar entries further in time