MariaDB [d_dar6hd3]> insert into menu_bg (group_id) values ('3');
ERROR 167 (22003): Out of range value for column 'id' at row 1

MariaDB [d_dar6hd3]> describe menu_bg;
+-----------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+---------------------+------+-----+---------+----------------+
| id | tinyint(3) unsigned | NO | PRI | NULL | auto_increment |
| parent_id | tinyint(3) unsigned | NO | | 0 | |
| title | varchar(255) | NO | | | |
| url | varchar(255) | NO | | | |
| class | varchar(255) | NO | | | |
| position | tinyint(3) unsigned | NO | | 0 | |
| group_id | tinyint(3) unsigned | NO | | 1 | |
| sub_exist | enum('1','0') | YES | | 0 | |
+-----------+---------------------+------+-----+---------+----------------+
8 rows in set (0,001 sec)

MariaDB [d_dar6hd3]> insert into menu_bg (group_id) values ('3');
ERROR 167 (22003): Out of range value for column 'id' at row 1

FIX

alter table menu_bg modify id SMALLINT(3) unsigned NOT NULL AUTO_INCREMENT;