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Oracle Troubleshooting

ORA-12224: TNS: no listener

Symptom:

When trying to connect to Oracle the following error is generated:

ORA-12224: TNS: no listener

Cause:

The connection request could not be completed because the listener is not running. This can be confirmed using the command:

lsnrctl status

on the database server.

Remedy:

• Start the listener on the remote machine. (Use ‘lsnrctl start’).

• If the server name has recently been changed then try running ‘Net 8 Configuration Assistant’ and select ‘Listener Configuration’. Work through the dialogs without changing anything and it will automatically update the server name. The listener can then be started. (Oracle 8 - but may apply to earlier versions.)

• Ensure that the supplied destination address matches one of the addresses used by the listener - compare the TNSNAMES.ORA entry with the appropriate LISTENER.ORA file.