Short tip: Changed Owncloud CardDAV/CalDAV URLs
Recently I had issues with configuring CardDAV-Sync and CalDAV-Sync along with Owncloud after a fresh Android installation. Specifying the well-known URLs just produced several error messages inside the app:
https://my-server.tld/owncloud/remote.php/caldav/principals/USER/ https://my-server.tld/owncloud/remote.php/carddav/principals/USER/
In the logs I saw a lot of messages about missing sub folders. After searching on the internet, I had a deeper look at the Owncloud web interface and spotted that the URLs have changed.
The following URL schemas worked for me:
https://my-server.tld/owncloud/remote.php/dav/ https://my-server.tld/owncloud/remote.php/dav/addressbooks/users/USER/contacts/
The folder name contacts needs to be replaced by the name of your addressbook.