RMAN errors out with ORA-01008: not all variables bound

One of our DB has a problem with RMAN backups with the error as below.

DBGSQL:     TARGET> select count(*) into :dbstate from v$parameter where lower(name) = '_dummy_instance' and upper(value) = 'TRUE'
DBGSQL:        sqlcode = 1008
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-00554: initialization of internal recovery manager package failed
RMAN-06003: ORACLE error from target database:
ORA-01008: not all variables bound

This is frustrating when doing any task with RMAN, even you can't log in to RMAN prompt as it says initialization of internal recovery manager package failed. The database version here is 11.2.0.2.0. Oracle support says this is related to bug 9877980 which happens when cursor sharing is set to force or similar.

We have cursor_sharing set to force. So obviously we have hit a bug.
The possible workaround is to just flush the shared pool. Yes, just flush the shared pool.

SQL> alter system flush shared_pool;
System altered.

Now you will be able to connect to the database through RMAN without any issues.

The detailed notes can be obtained from Oracle Support Doc ID 1472116.1.
By the way, the issue is fixed in 11.2.0.3 and above.

Happy troubleshooting...