"datafile %s has been restored from an optimized RMAN backup."
*Cause: Flashback Database could not flash back the file because it
was restored from an RMAN optimized backup with deallocated
objects. Flashback cannot revert the file to a time before
the last deallocation in the datafile backup.
*Action: Restore the file from a backup prior to the Flashback target
SCN or time and then retry the command.