All MySQL error codes

MySQL error code

MySQL error 1055

MySQL server error 1055 is ER_WRONG_FIELD_WITH_GROUP, reported with SQLSTATE 42000.

'%s' isn't in GROUP BY

Error	1055
Name	ER_WRONG_FIELD_WITH_GROUP
SQLSTATE	42000
Group	Server errors

How to fix it

Explained step by step, with a query you can run

column "x" must appear in the GROUP BY clause or be used in an aggregate function

In other databases

Source: MySQL 8.4 Error Reference