Registration problem

[Grinder]

I have an problem on my board that new members can not register because the error is " The email address is already in use by another member"

I used to use ipb 3.1.2 and on that version the error started to occur. So I thought to upgrading to ipb 3.1.4 would prevent that error but that was not the case. The error keeps there.

Please give me some advice to prevent this error.

 

[Grinder]

Ok, I found it.

Seems that converge was enabled in my acp so I disabled it and new registration works again.