HttpException: HTTP 415 - How to find calendar entry which causes it

[varac]

I have a HTTP 415 error every time I try to sync my calendar:

07-30 07:40:51.937  6268  6396 I davx5   : [sync.CalendarSyncer] Synchronizing calendar #20, URL: https://cloud.systemli.org/remote.php/dav/calendars/varac/personal/
07-30 07:40:51.939  6268  6396 I davx5   : [sync.SyncManager] Preparing synchronization
07-30 07:40:51.940  6268  6396 I davx5   : [resource.LocalCalendar] Processing deleted exceptions
07-30 07:40:51.955  6268  6396 I davx5   : [resource.LocalCalendar] Processing dirty exceptions
07-30 07:40:52.117  6268  6396 I davx5   : [sync.SyncManager] Querying server capabilities
07-30 07:40:52.262  6268  6396 I davx5   : [sync.CalendarSyncManager] Calendar accepts events up to 9 MB
07-30 07:40:52.263  6268  6396 I davx5   : [sync.CalendarSyncManager] Calendar supports Collection Sync: true
07-30 07:40:52.264  6268  6396 I davx5   : [sync.SyncManager] Processing local deletes/updates
07-30 07:40:52.276  6268  6396 I davx5   : [sync.SyncManager] Removed 0 record(s) from server
07-30 07:40:52.651  6268  6396 I davx5   : [sync.SyncManager] Uploading modified record 15131 -> e271c387-efa0-4c1f-a2e6-960ea946dcc7.ics (ETag=c66b37c40871510fe3678f428c435a43, Schedule-Tag=null)
07-30 07:40:52.825  6268  6396 E davx5   : [sync.SyncManager] HTTP/DAV exception
07-30 07:40:52.825  6268  6396 E davx5   : EXCEPTION at.bitfire.dav4jvm.exception.HttpException: HTTP 415 
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.dav4jvm.DavResource.checkStatus(DavResource.kt:3)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.dav4jvm.DavResource.checkStatus(DavResource.kt:1)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.dav4jvm.DavResource.put(DavResource.kt:26)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.dav4jvm.DavResource.put$default(DavResource.kt:27)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.uploadDirty$lambda$11(SyncManager.kt:106)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.$r8$lambda$p1AXHeB4C3ojuGXxamkZ7wEYlGk(SyncManager.kt:1)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager$$ExternalSyntheticLambda8.invoke(R8$$SyntheticClass:13)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.remoteExceptionContext(SyncManager.kt:1)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.uploadDirty(SyncManager.kt:16)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager$uploadDirty$1$1.invokeSuspend$lambda$0(SyncManager.kt:1)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager$uploadDirty$1$1.$r8$lambda$dSBHcVSiwh1VtvJmGJnKlGwFFXY(SyncManager.kt:1)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager$uploadDirty$1$1$$ExternalSyntheticLambda0.invoke(R8$$SyntheticClass:9)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.localExceptionContext(SyncManager.kt:8)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager$uploadDirty$1$1.invokeSuspend(SyncManager.kt:21)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:9)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:111)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.EventLoopImplBase.processNextEvent(EventLoop.common.kt:145)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.BuildersKt.runBlocking(Unknown Source:105)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.BuildersKt.runBlocking$default(Unknown Source:3)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.uploadDirty(SyncManager.kt:2)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.CalendarSyncManager.uploadDirty(CalendarSyncManager.kt:73)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.performSync$lambda$3(SyncManager.kt:65)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.$r8$lambda$yWVzYZpyC2XofwJvr99jweeoFzg(SyncManager.kt:1)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager$$ExternalSyntheticLambda4.invoke(R8$$SyntheticClass:3)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.unwrapExceptions(SyncManager.kt:2)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.SyncManager.performSync(SyncManager.kt:20)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.CalendarSyncer.sync(CalendarSyncer.kt:153)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.Syncer.onPerformSync(Syncer.kt:124)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.worker.BaseSyncWorker$doSyncWork$2.invokeSuspend$lambda$1$lambda$0(BaseSyncWorker.kt:16)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.worker.BaseSyncWorker$doSyncWork$2.$r8$lambda$Uh1BtWdiR0o_egjO77Vb3A93BTA(BaseSyncWorker.kt:1)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.worker.BaseSyncWorker$doSyncWork$2$$ExternalSyntheticLambda0.invoke(R8$$SyntheticClass:16)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.InterruptibleKt$runInterruptible$2.invokeSuspend(Interruptible.kt:75)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.InterruptibleKt$runInterruptible$2.invoke(Interruptible.kt:13)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undisp
07-30 07:40:52.825  6268  6396 E davx5   : atched.kt:5)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.BuildersKt.withContext(Unknown Source:41)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.InterruptibleKt.runInterruptible$default(Interruptible.kt:9)
07-30 07:40:52.825  6268  6396 E davx5   : 	at at.bitfire.davdroid.sync.worker.BaseSyncWorker$doSyncWork$2.invokeSuspend(BaseSyncWorker.kt:497)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:9)
07-30 07:40:52.825  6268  6396 E davx5   : 	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:111)
07-30 07:40:52.825  6268  6396 E davx5   : 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
07-30 07:40:52.825  6268  6396 E davx5   : 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:644)
07-30 07:40:52.825  6268  6396 E davx5   : 	at java.lang.Thread.run(Thread.java:1012)

How can I find the specific calendar entry which causes the error (record 15131 -> e271c387-efa0-4c1f-a2e6-960ea946dcc7.ics (ETag=c66b37c40871510fe3678f428c435a43)) ?
I followed https://www.davx5.com/faq/how-to-debug but I can only find information about calendar #20, but not about the specific calendar entry:

$ adb shell content query --uri content://com.android.calendar/calendars | grep '_id=20'
Row: 8 account_type=bitfire.at.davdroid, mutators=NULL, ownerAccount=varac@..., allowedReminders=0,1,2, cal_sync3=NULL, cal_sync2=NULL, isPrimary=1, maxReminders=5, cal_sync1={"type":"SYNC_TOKEN","value":"http:\/\/sabre.io\/ns\/sync\/27643"}, cal_sync10=NULL, [email protected], cal_sync7=NULL, cal_sync6=NULL, canPartiallyUpdate=0, cal_sync5=NULL, sync_events=1, cal_sync4=NULL, canOrganizerRespond=1, calendar_color=-23736, cal_sync9=NULL, calendar_location=NULL, cal_sync8=NULL, dirty=NULL, visible=1, calendar_timezone=NULL, calendar_access_level=700, allowedAvailability=0,1, _sync_id=NULL, deleted=0, name=https://cloud.systemli.org/remote.php/dav/calendars/varac/personal/, canModifyTimeZone=1, _id=20, calendar_color_index=NULL, allowedAttendeeTypes=0,2,1,3, calendar_displayName=personal

[ArnyminerZ]

Well, I can't help much, but I can point you in the right direction I think.

You can find that entry inside of e271c387-efa0-4c1f-a2e6-960ea946dcc7.ics, ETag=c66b37c40871510fe3678f428c435a43. You can do that using PROPFIND commands of curl or similar, manually making each request, and checking for the responses, if the problem comes from the server.

If the problem comes from the Android device, which is what I believe is happening, remember that you can also fetch individual events with

adb shell content query --uri content://com.android.calendar/events

I think the issue is more related to an event than a calendar.

It's not much, but I'm currently not at home, and can't help more 😅

[rfc2822]

When you enable verbose logs in DAVx5 settings, it provides much more details about what's being uploaded etc (both in the generated log file but also in adb logcat). You should get enough information then.

Also, the error notification should have a "View item" action when you expand it, which should open the approriate app.

[varac]

Thanks @ArnyminerZ and @rfc2822, good to know for next time, but luckily the issue fixed without any intervention (?), although I know that usually things don't fix themselves :)
I'll close this for now and reopen it once I hit this again.