ORA-12514 error after patch installation
I have installed the Oracle 10.2.0.3 patch on top of 10.2.0.2 on my Oracle 10g instance. After that when I am trying to log in to Oracle I am kicked out with a ORA-12514 error: "ORA-12514: TNS:listener does not currently know of service requested in connect." I had narrowed this down to a resolution provided for this error on this site but it was no help. Please help me.
This error usually means that you are attempting to connect to the database via the listener and either the listener is not running or it cannot find the SERVICE_NAME specified in the connect string. Check to see that the listener is running and that it has started with no errors. You can review the listener log file usually located in $ORACLE_HOME/network/admin (unless you have the environment variable $TNS_ADMIN set, in which case it can be found at that location instead).
It is also possible that the database has not registered with the listener. Try restarting the database and try connecting again to see whether this resolves the problem. Note that it can take 60 seconds for a database to register with a listener.
Finally, check the sqlnet.ora file to determine whether NAMES.DIRECTORY_PATH = (HOSTNAME). Comment this line out and try connecting again. When this parameter is set to HOSTNAME, SQL*Plus is using only the hostname to attempt to identify the remote database SID and resolve the address.
This was first published in January 2007