ORA-12514 TNS listener does not currently know of service requested in connect descriptor

Error from Recovery Catalog Database – ORA-12514 | Could not connect to RMAN Catalog Database

Example :  c:\> rman target / catalog rcat/password@orcl

Error: TNS: listener does not currently know of service requested in connect descriptor

recovery_catalog_error

The typical solution when you encounter this error is to check the TNSNames.ora file in the $ORACLEHOME\NETWORK\ADMIN directory to correct any typo errors

But what if your recovery catalog database was working perfectly earlier and no changes were done to the TNSNames.ora file. If yes, below steps should help you

Connect to the Recovery Catalog Database

c:\> set ORACLE_SID=catdb
c:\> sqlplus target /

You could end up getting an error message : Connected to an Idle Instance

Startup the Instance

You can start the Instance with below command

c:\> oradim -STARTUP -SID <SID> -STARTTYPE inst -PFILE <fullpath of the INITsid.ora file>

Example: oradim -STARTUP -SID catdb -STARTTYPE inst -PFILE c:\oracle\product\10.1.0\db_1\database\INTIcatdb.ora

The Recovery Catalog database instance should now be started