In log/errors I get the following message:
DB Error: [1054] Unknown column 'authentication_scheme' in 'field list' (SQL Query: SELECT id as abookid,name,username,password,url,presetname,sync_token,authentication_scheme,(now() > last_updated+refresh_time) as needs_update FROM carddav_addressbooks WHERE `id`='1') in /var/www/roundcubemail/program/lib/Roundcube/rcube_db.php on line 541