ICSdroid is a sync adapter which must not be moved to the SD card: Otherwise, it’s possible that the application is not loaded somewhen. At this time, the Android account manager sees orphaned accounts (belonging to the ICSdroid package that is not available [because it’s not loaded]).
I have now added android:installLocation="internalOnly" to the AndroidManifest which should fix that problem.
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.