ORA-12541: TNS:no listener...


You get this error when accessing a database in Iron Speed Designer, typically in the Application Wizard:

Unable to connect to XXX server: Error: ORA-12541: TNS:no listener


This error could be caused due to the following:

1. This error could be caused by because of a firewall software on your system such as ZoneLabs ZoneAlarm or Norton Firewall.  In the firewall software, grant 'server' permissions to 'oracle.exe' and 'tnslsnr.exe'.  You can also temporarily turn off the firewall software to test. Also make sure to allow port 1521 for local system IP in settings of ZoneAlarm or the firewall software.

2. 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.

3. Make sure a listener is running.  Either use lsnrctl to start the listener or startup the appropriate Windows service.

If the listener is running correctly, make sure that the connect information provided (hostname, portnumber) matches with the information in the listener.ora file or the local_listener database parameter.

If you do not know the host and port information of a given connection string, you can use the tnsping command line tool to get this information:

C:\>tnsping ORA920

TNS Ping Utility for 32-bit Windows: Version – Production

Copyright (c) 1997 Oracle Corporation. All rights reserved.

Used parameter files:


Used TNSNAMES adapter to resolve the alias


OK (200 msec)

Using the host (DEV01) and port (2491) information, go to the server identified by HOST.

Open a shell or command prompt, and check if there is a process listening on the port identified by PORT.

c:\>netstat –a


TCP DEV01:2491 DEV01.eu.dbmotive.com:0 LISTENING


See Also

Part VII:  Troubleshooting Applications

Application Generation and Compilation Error Messages