I am using Firebird-2.5.3.26778_0_Win32 on Windows 8.1 64-bit.

When attempting to restore a database using the restore method of the service API (via IBExpert if that matters) I am getting the following error:

gbak:    restoring privilege for user PUBLIC 

IBE: Invalid insert or update value(s): object columns are constrained - no 2 table rows can have duplicate column values.

To me, this seems to indicate that Firebird got a duplicate key error while attempting to restore user privileges.

Not sure how this can be possible.

To be absolutely certain, I manually activated all of the user indices in the database without problem.

Any suggestions?

It is a very small database. I can send it to anyone who might be interested in taking a look at it.