ORA-12224: TNS:no listener

when database listener was down and you are trying to connect from other host.you will recieve this error.

sqlplus apps/apps

SQL*Plus: Release 8.0.6.0.0 - Production on Thu Apr 18 18:18:08 2013

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ERROR:
ORA-12224: TNS:no listener.

Cause: Database listener was down.

solution: Just bring up database listener and try to connect to database.


If you want to learn basic,please click on the below link.
What happen when you startup database?Click here to check in detail.