Thanks for the tip regarding version 3.0 and 4.0. The complete trace DAVdroid write to SD-Card contains “VERSION:4.0”. Owncloud somehow falsly converts it to “VERSION:3.0” without converting the values properly. So this ticket can be closed. Thanks for your help.
P.S.: This is my oc workaround: https://github.com/s3menzer/contacts/commit/5e5a813f8eaff6a77dc2b2f9abb533a5f973a5db
@akero Hello, please see the original post for RC1:
If you’re upgrading from DAVdroid 0.9.x there are migration routines that try to update all your settings and resources to the newest version. If you previously had an alpha or beta version, you need to uninstall and reinstall the latest version.