Oracle Message ORA-10873 - file string needs to be either taken out of backup mode or media recovered

ERRORfile string needs to be either taken out of backup mode or media recovered
CAUSEAn attempt was made to open a database after an instance failure or SHUTDOWN ABORT interrupted an online backup.
ACTIONIf the indicated file is not a restored backup, then issue the ALTER DATABASE END BACKUP command and open the database. If the file is a restored online backup, then apply media recovery to it and open the database.