I have just installed the 11g client on a server with the 8.1 and 9.2 clients already installed. This server is used to run scheduled console apps, many of which have not been recompiled for years. They now give:

Initialization error
Could not locate OCI dll

OracleHomeKey: SOFTWARE\ORACLE\KEY_OraOdac11g_home1
OracleHomeDir: C:\app\david.g.smith\product\11.1.0\client_1

I know I can recompile them, or pass OCIDLL="d:\oracle\ora92\bin\oci.dll" on the command line. Is there another option, something that doesn't require modifying each of these jobs?

Thanks.

Direct Oracle Access will use the Primary Oracle Home by default. This is the home that is listed first in the PATH environment variable. You can modify the PATH to change the Primary Oracle Home.

Thanks so much. That worked.

Hello !! I had the same trouble.
Here is the solution:

1) Copy the OCI.DLL file from: C:\app\david.g.smith\product\11.1.0\client_1 to C:\app\david.g.smith\product\11.1.0\client_1\bin
2) Open PL/SQL Developer.
3) Close the connection window
4) Go to Tools -> Preferences
5) Click on Oracle -> Connections
6) Put your OracleHomePath into OracleHome
7) Put your OCI.DLL path on OCI library:
C:\app\david.g.smith\product\11.1.0\client_1\bin\oci.dll
8) Click on Force OCI7 mode on OCI8
9) Click Apply, Click Ok. Restart the PL/SQL Developer and try to connect.

It worked for me.

Good luck!!