Prevent Registration Where Role is None?

Hmm – if they have no role, it may be that they are coming in through some other way and adding that action will not help.

What plugins do you have active ?

also are you sharing a wp user database with another system?

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)