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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.

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: 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.