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ORA-12541 after Oracle 10g Client re-install

I'm getting "ORA-12541:TNS:no listener" when trying to connect to Oracle in Visual Studio 2005 / SQL Server 2005 Reporting Services. This was not happening until I recently did a re-install of Oracle 10g Client / ODP.Net (via OUI). I can connect via Toad and have run the ODP.NET setup (after running the client setup). I'm using a Windows XP Professional workstation. Other developers are able to connect fine; it's not the database. I do not have any way to start or stop the listener, not in my services, and the DOS command is not on my machine. Very frustrating....

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Since you've mentioned that others can connect to the database, the problem likely stems from a configuration setting on your workstation. In your TNSNAMES.ORA file, make sure the value of HOST and PORT match the value of HOST and PORT in the LISTENER.ORA file on the database server. If this does not resolve the problem, change HOST in your tnsnames.ora file to use an IP address of the database server rather than host name. You may also want to set the environment variable TNS_ADMIN on your workstation and server to ensure you are using the correct set of configuration files. Finally, firewalls on both the client and server can cause this error. Ensure that firewalls are configured correctly to allow connections to the database server.

This was first published in May 2007

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