Expression #13 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'jean.pl.name' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
SELECT
p.*, pl.name, pl.path
FROM
sys_pages AS p LEFT JOIN sys_pages_languages AS pl ON (p.id=pl.id_page)
WHERE
pl.id_language=1 AND p.active='Y' AND pl.name != "" group by p.id
ORDER BY p.list
;