"cannot FLASHBACK DATABASE during instantiation of a logical standby"
*Cause: The command was not permitted because the controlfile indicates
the database was in the process of becoming a logical standby database
but the controlfile conversion had not completed.
*Action: If in the process of creating a logical standby database, perform the
remaining instantiation procedures to completion. If this flashback
operation followed a Data Guard failure, permit the errant Data Guard
operation to successfully complete. Once the instantiation is
complete, reissue the flashback operation.