An Error Was Encountered

Error Number: 1055

Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'ilmuhewa_iklan01.ads_tags.tag' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

SELECT tag, slug, counter FROM ads_tags WHERE counter>0 GROUP BY slug ORDER BY counter DESC, tag ASC LIMIT 35