Netbackup Oracle DB backup failing with error 6

Today we have faced a backup failure of a Oracle DB and later was able to fix the issue following the steps below.

Error
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RMAN-00554: initialization of internal recovery manager package failed
RMAN-04004: error from recovery catalog database: ORA-12516: =
TNS:listener could not find available handler with matching protocol =
stack
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ERROR : ORA-12516: TNS:listener could not find available handler with matching protocol stack

CAUSE : One of the most common reasons for the TNS-12516 and/or TNS-12519 errors being reported is the configured maximum number of PROCESSES and/or SESSIONS limitation being reached. When this occurs, the service handlers for the TNS listener become "Blocked" and no new connections can be made.

SOLUTION :
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1.Check maximum value for processes and sessions using below command :
select name, value from v$parameter where name in (‘processes’,'sessions’);

2.Check current process and session and maximum limitation using below command :
select * from v$resource_limit;

3. Increase your process and session, for example to 300 using below command :
alter system set processes=300 scope=spfile;
alter system set sessions=300 scope=spfile;

4. You need to restart database to take effect.