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