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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.ORAentry with the appropriateLISTENER.ORAfile.
This page represents one page of many pages of notes I made whilst working with Oracle 7 through to 10i. I now no longer work with Oracle databases, but hope that these notes will continue to be of benefit to others.
About the author: Brian Cryer is a dedicated software developer and webmaster. For his day job he develops websites and desktop applications as well as providing IT services. He moonlights as a technical author and consultant.