ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode

Problem Description

Using Rman to backup a NOARCHIVELOG failed with error :

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================

RMAN-03009: failure of backup command on ORA_DISK_1 channel at 06/20/2013 16:48:31
ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode


Cause
Startup mount force cause datafile was not closed cleanly


Solution

Following commands will guarantee that the database is in a consistent state for a backup:

RMAN> shutdown immediate;
RMAN>  STARTUP FORCE DBA;
RMAN> shutdown immediate;
RMAN> STARTUP MOUNT;

RMAN> backup database;