OK, found the external file in /storage/emulated/0/Android/data/at.bitfire.davdroid/files/ and succeeded in downloading it. In the first lines I see 2018-01-23 14:48:07 638 [syncadapter.SyncAdapterService] org.dmfs.tasks sync of Account {name=mymail@mydomain, type=bitfire.at.davdroid} has been initiated PARAMETER #0 = upload 2018-01-23 14:48:07 638 [AccountSettings] Account mymail@mydomain has version 8, current version: 8 2018-01-23 14:48:07 638 [syncadapter.TasksSyncAdapterService] Adding local task list PARAMETER #0 = CollectionInfo(url=https://calendar.mydomain/dav/home/mymail@mydomain/1516630021692-46306/, id=3, serviceID=1, type=CALENDAR, readOnly=false, forceReadOnly=false, displayName=aucheiner, description=auch ein Kalender, color=null, timeZone=null, supportsVEVENT=true, supportsVTODO=true, selected=true, source=null, confirmed=false) 2018-01-23 14:48:07 638 [AndroidTaskList] Creating local task list: list_access_level=0 list_name=aucheiner _sync_id=https://calendar.mydomain/dav/home/mymail@mydomain/1516630021692-46306/ visible=1 account_type=bitfire.at.davdroid list_color=-3937682 list_owner=mymail@mydomain sync_enabled=1 account_name=mymail@mydomain 2018-01-23 14:48:07 638 [syncadapter.TasksSyncAdapterService] Adding local task list PARAMETER #0 = CollectionInfo(url=https://calendar.mydomain/dav/home/mymail@mydomain/calendar/, id=4, serviceID=1, type=CALENDAR, readOnly=false, forceReadOnly=false, displayName=Werner Flamme, description=null, color=null, timeZone=null, supportsVEVENT=true, supportsVTODO=true, selected=true, source=null, confirmed=false) 2018-01-23 14:48:07 638 [AndroidTaskList] Creating local task list: list_access_level=0 list_name=Werner Flamme _sync_id=https://calendar.mydomain/dav/home/mymail@mydomain/calendar/ visible=1 account_type=bitfire.at.davdroid list_color=-3937682 list_owner=mymail@mydomain sync_enabled=1 account_name=mymail@mydomain 2018-01-23 14:48:07 638 [syncadapter.TasksSyncAdapterService] Synchronizing task list #5 [https://calendar.mydomain/dav/home/mymail@mydomain/calendar/] I do not see the part between “Account has been initiated” and the construction of the URLs, so I still don’t know how this is put together.