MySQL error in file: /engine/modules/thanks.php at line 77

Error Number: 1267

The Error returned was:
Illegal mix of collations (utf8mb4_0900_ai_ci,IMPLICIT) and (utf8mb4_general_ci,IMPLICIT) for operation '='

SQL query:

SELECT t.user_name, u.user_group FROM dle_thanks_post AS t, dle_users AS u WHERE t.user_name=u.name AND t.post_id='41813' ORDER by t.id ASC