Database Error Messages

There are two possible cause for this error:

1. The flashback log can only be either in DB_RECOVERY_FILE_DEST or DB_FLASHBACK_LOG_DEST but not both. As flashback database is already on without a DB_FLASHBACK_LOG_DEST, there will already be flashback logs inside DB_RECOVERY_FILE_DEST. Can not set DB_FLASHBACK_LOG_DEST dynamically now because flashback logs will be in both places after the operation.
2. An attempt was made to change DB_FLASHBACK_LOG_DEST with the ALTER SYSTEM command when flashback database is on

Set DB_FLASHBACK_LOG_DEST dynamically before turning on flashback database.