--- In ib-support@y..., "zifnabbe" <zifnabbe@u...> wrote:

> Hi,
>
> I get the following error when I try to create a unique constraint,
> what does it mean? :
>
> ISC ERROR Code 335544349
>
> attempt to store duplicate value (visible to active transactions) in
> unique index "RDB$INDEX_16"
>
> I've emptied the table on which I want to put that constraint and
> I've nowhere set already such a unique constraint...
>

Tom, what IB or FB version do you use? This exception mean you have
damaged RDB$FORMATS table or index RDB$INDEX_16 on this table. I
remember there was bug in some builds near FB beta2 which can cause
such a problem and in current builds it is fixed. To repair such a
database you have to backup it and restore. Into another file or
having copy of original database, of course.

Best regards, Alexander V.Nevsky.