DEBUG: error in query
  QUERY = SELECT U.*, IFNULL(H.refdate, '1970-01-01 01:00:01') AS refdate FROM cms_module_feusers_users U LEFT JOIN cms_module_feusers_history H ON U.id = H.userid LEFT JOIN cms_module_feusers_properties P2 ON U.id = P2.userid AND P2.title = 'nachname' WHERE expires > '2017-10-18 05:54:54' GROUP BY U.id ORDER BY P2.data ASC LIMIT 0, 100
  Error = Expression #6 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'usr_ud13_6_2.H.refdate' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by