MySQL sql_mode - Get and Set sql_mode Settings to solve

Check your current sql_mode

SELECT @@GLOBAL.sql_mode;         
or, 
SELECT @@sql_mode;

Edit your my.cnf and remove  "ONLY_FULL_GROUP_BY". if you don't have sql_mode, just add sql_mode to .conf. Restart mysql server.

sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION