[_ck_]

Database error: []

SELECT * FROM bb_online WHERE user_id = LIMIT 1

Caller: online_logout

The user_id is empty in this case which causes the error.

The question is why it’s empty.

This could be a cookie problem, this could be an alpha bug.

If you have no plugins running and switching to the default template does not make the error go away, it’s a bug and should be reported on TRAC (along with your configuration if possible, server type, PHP, etc)