ORA-12541 TNS: 'No listener error' Troubleshooting

Here are some steps to troubleshoot a "no listener" error.  Very often the listener is not using the PORT or HOST
that the client expects.  This document should help in finding the cause:

Troubleshooting Guide for ORA-12541 TNS: No Listener  (Doc ID 2059450.1)

Sample of some quick listener checks:

UNIX:

1)  Grep for tns listener process.

     ps -ef | grep tns

     Confirm the listener process is present.

     Confirm the listener is running under:

        A)  The correct name (LISTENER, LISTENER_SCANx, etc)

           The correct $ORACLE_HOME/bin (GRID, RDBMS_HOME)

2)  Check netstat output and confirm the port/address:

      netstat -an | grep <listener port here>