Procedure A - Check the Environment Variables
Check the Window Environment Variable for the Oracle path to make sure it is the same as the actual install path.
1. Open Windows cmd prompt as Admin.
2. Type in "
path" and press Enter.
3. Look for the
%Oracle_Home%\bin path.
e.g. - C:\app\<user_name>\Product\12.2.0\client_1\bin
or

4. Compare that path to the actual installation path.
5. If they are different, the path in the Environment Variables will need to be fixed to match the actual install path. A mistake in editing could affect other applications so if you are not familiar with how to edit, it is better to ask your IT Admin to fix or reinstall the Oracle client properly.
Procedure B - Which database connection did you use?
If you tried using the ODBC connection, try using the OCI (New Oracle Connection). If you do not know the TNS server name it can be found in the
tnsnames.ora file. Consult an Oracle DBA for more information.
Procedure C - What permissions do you have?
1. Go to the Oracle Client folder in Windows Explorer.
2. Right-click on the folder.
3.
*On the security Tab, Add “
Authenticated Users” and give this account
Read & Execute permission.
4. Apply this security for all folders, Subfolders, and Files (
IMPORTANT).
5. Don’t forget to
REBOOT your machine; the error will persist until the machine has been restarted.
*Note: Check with your IT before changing any permission settings.
Procedure D - How many instances of Oracle do you have installed?
Oracle may find it difficult to navigate and select the correct version if it has more than one version installed or if there are incomplete/stagnant clients installed. If you only need one of them it is better just to remove them all and reinstall the one that is needed to effectively clean up the environment.
Procedure E - Do you have the correct bitness client installed?
One way to check to see if you have the right bitness drivers installed is to set up the DSN connection through the ODBC Admin and see if any drivers populate for either the 32-bit or 64-bit connections. It's recommended to use a 64-bit client.