ERROR: Unable to execute query

SELECT DISTINCT *,count(gt.group_topic_group_id) AS `total` FROM
               `group_topics` AS gt,
               `groups` AS g WHERE
                gt.group_topic_group_id=g.group_id
                GROUP BY gt.group_topic_group_id
                ORDER BY `total` DESC

Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'filmesg_tb.gt.group_topic_id' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by