When restore fails to activate (and recreate) deferred index (typically due to insufficient temporary disk space), gbak returns FAIL result code (1) only when failed index is related to referential constraint. Failed user index is reported only to stderr (log if captured) but gbak returns result code 0. When restore is managed by script(s), it's not possible to easily detect this situation, and it's possible that database could be used with inactive index in production.