Oracle Error Message
ORA-38869: datafile string has been restored from an RMAN backup with undo block compression.
Reason for the Error
Flashback Database could not flash back the database because a file was restored from an RMAN backup with undo block compression, and the Flashback target was to a time when the missing undo may be needed to open the database.
Solution
Restore an earlier backup of the file and retry the command or Flashback to a later time.