- ical4android: upgrade to ical4j/2.1.3 brings VTIMEZONE caching (performance improvement)
- build tools 27 works around bug of some custom ROMs that causes crashing apps and boot loops
DAVdroid 1.9 Release Notes
If you need DAVdroid for an older Android version, we recommend to use the F-Droid Archive. The latest formally compatible versions may not work – in this case, you can go back until you find a working version. If ever possible, updating your Android version using a Custom ROM is much better than using old app versions (just think about TLS ciphers which are not supported by old Android versions yet, WiFi/BT vulnerabilities etc.).
Target Android 8.1:
sync_versionfield for tasks
Please note that if you upgrade from v <1.9 to 1.9.4 ≤ v < 1.9.10 directly, the upgrade will still fail (causing all collections to be shown as read-only without possibility to change that). In this case, you have to uninstall DAVdroid and install it again (or to delete all DAVdroid accounts, clear app storage and add the accounts again).
Upgrading from any version, including <1.9, to 1.9.10 should work without problems.