At some occasions (especially when booting), Android looks for orphaned accounts which are not associated to a sync adapter. Unfortunately, this check is sometimes run before DAVx⁵ is available.
So, if this check doesn't find DAVx⁵ for whatever reason, it thinks that all DAVx⁵ accounts are orphaned and deletes them, including all your local contacts, calendars and tasks (together with all unsynced changes). This problem is known for at least these cases:
- when DAVx⁵ has been moved to the SD card / USB storage (although this is forbidden by the app manifest),
- when the device is booted into safe mode, and
- because of a Google Play bug which may affect users who have got DAVx⁵ via Google Play on
- many Android 4.4.x devices, regardless of the manufacturer, for instance LG G3 (LG-D855) with Android 4.4.2,
- and some other devices.
- DAVx⁵ must not be moved to external storage (SD card / USB storage).
- Upgrade your device to the latest available Android version (if your firmware is really old, you may consider a custom ROM).
- If you boot into safe mode, be prepared that all local DAVx⁵ data (including unsynced changes) will be lost. At the next synchronization, all data will be downloaded from the server again.
- You may consider to install DAVx⁵ from another source (e.g. F-Droid).