'topic_views' column in 'topics' table has MEDIUMINT 8 type so max value is 16777215 and it is quite possible to reach this max value with bots or zabbix, etc. Thus topic becomes inaccessible (SQL ERROR [ mysqli ] Out of range value for column 'topic_views' at row 1 [1264]).

Can it be extended to something more adequate like INT 11 ?

It wouldn't be a bad idea to check max value and do not try to update counter in this case too.

Thank you.