Visual Studio ODP Unmanaged Driver - Failed to find the default tnsnames.ora file (12c )

Question

I'm developing an app in Visual Studio 2013 that connects to a Oracle Database. I have to use the "Unmanaged Driver". When I'm trying to create a new connection in a dataset, when I chose the "Managed Driver" all work fine: the tnsnames.ora is found. But when I select the "Unmanaged driver" all fails, it send me a message like " Failed to find the default tnsnames.ora file"

I already - Uninstalled all old Oracle Clients - Clean all environment variables - Reinstalled Oracle client, ODP tools for Visual Studio

Nothing seems to work. Any ideas ?

Answer 1

you should go to the folder containing the machine.config file. this file is found in %windir%\Microsoft.NET\Framework64\[version]\config\machine.config

make sure you have the following value.

<oracle.manageddataaccess.client>
    <version number="4.121.2.0">
      <settings>
        <setting name="TNS_ADMIN"value="E:\app\client\USERWINDOW\product\12.1.0\client_1\network\admin" />
      </settings>
    </version>
</oracle.manageddataaccess.client>

Also, refer to this post on Where Is Machine.Config?

Answer 2

You can ignore that message and simply use EZ Connect to connect (providing host, port, service_name).

Or you can find a valid TNSNAMES.ORA with your aliases in it, and copy it to: [ORACLE_HOME_WHERE_ODT_IS_INSTALLED]\NETWORK\ADMIN

Since Managed Driver can find TNSNAMES.ORA this means that TNS_ADMIN is set in the machine.config. When you connect using managed provider, the connection dialog will show you where it is finding the TNSNAMES.ORA and you can copy it over.