RMAN-06900: WARNING: unable to generate V$RMAN_STATUS or V$RMAN_OUTPUT row

When I was trying to connect rman appeared below error:

[oracle@oel6 ~]$ rman target /

Recovery Manager: Release 11.2.0.1.0 - Production on Tue Feb 10 15:06:05 2015

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

connected to target database: TESTDB (DBID=2647984357)
RMAN-06900: WARNING: unable to generate V$RMAN_STATUS or V$RMAN_OUTPUT row
RMAN-06901: WARNING: disabling update of the V$RMAN_STATUS and V$RMAN_OUTPUT rows
ORACLE error from target database:
ORA-19921: maximum number of 128 rows exceeded


RMAN>

This is due too many RMAN connections, if there is not going RMAN backup then we can simple kill that processes.

select 'kill -9 ' || b.SPID,
       a.USERNAME,
       a.MACHINE,
       a.LAST_CALL_ET,
       a.MODULE,
       a.SID,
       a.PROCESS,
       a.EVENT,
       a.ACTION,
       a.osuser
  from v$session a, v$process b
 where a.PADDR = b.ADDR
   and module like '%rman%'
 order by MODULE;

result:

then just kill that processes from operating system

[oracle@oel6 ~]$ kill -9 23285
[oracle@oel6 ~]$ kill -9 23283
[oracle@oel6 ~]$ kill -9 23617
[oracle@oel6 ~]$ kill -9 23646

[oracle@oel6 ~]$ rman target /

Recovery Manager: Release 11.2.0.1.0 - Production on Tue Feb 10 15:59:14 2015

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

connected to target database: TESTDB (DBID=2647984357)

RMAN>