Sometimes You can get ” ORA-12224: TNS:no listener ” error.
Details of error are as follows.
ORA-12224: TNS:no listener Cause: The connection request could not be completed because the listener is not running. Action: 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 (or TNSNAV.ORA if the connection is to go by way of an Interchange). Start the listener on the remote machine.
This error is related with the listener of database server, if you got this error, then check your database listener as follows.
$ lsnrctl status listener
Listener should be always started.
You can stop and start the Listener as follows.
$ srvctl start listener $ srvctl stop listener
$ lsnrctl stop listener $ lsnrctl start listener