I know from experience that a restore can sometimes leave indexes in a disabled state, and you would usually get an error when trying to activate it as it was left disabled during the restore phase due to a minor data issue. The errorlevel returned by GBAK is greater than 0 so you can detect when this has happened without having to check all the indexes.

We see this with our firebird databases on occasion, it’s preferable to the restore just failing and having to be run again without restoring indexes and manually identifying and dealing with the data issue then turning all the indexes back on again. It seems to be minor data issues that cause the index gets left disabled by GBAK, bigger issues and the restore will just stop with an error.