Can't initialize OCI. Error -1 - Windows 10

I can not connect to a oracle 10g database using the 32bit version on a 64bit operating system. I have installed the software using Admin privileges and I have even attempted to run the software with Admin privileges. I have triple checked all the connection parameter details, and I get the Can't initialize OCI. Error -1 error message when I attempt to connect. When I have TNS ping via the Toad software is just states that the listener is not found.

Many thanks


Do you have 32 bit Toad? (you should, if you want to use 32 bit Oracle client)
Is the folder with oci.dll in your system path? (it should be)
Is there any other oci.dll in your system path (this shouldn't be a problem but it has been known to cause problems in certain situations which I don't recall the exact details of - if you have more than one client, you might try temporarily taking the others out of path, either by changing path or renaming the other folders with the client)

This just happened to me. I made a connection with a 12cR2 client, then needed to connect with a 10g client. It worked fine after restarting Toad and then connecting with a 10g client after the restart.

Sometimes these Oracle DLL's don't unload properly, so switching can be (but isn't always) problematic. It tends to depend on which client you are switching from/to.

Hi that’s for your help. I do have the 32bit version. The oci.dll is in the system path (C:\oracle\product\10.2.0\client_1\BIN) and no it is not duplicated elsewhere. I’ve restarted toad on a number of occasions and it doesn’t appear to have any effect. I have also made sure that no other client is running or has been running, and that hasn't made any difference.

John: I'm running into same issue on windows 10 (64 bit). I've multiple oracle clients but did not had any problem until yesterday when TOad 14 (beta version got updated). I tried all possible solutions, checked environment variables PATH (made client ahead of all other values), TNS_ADMIN, ORACLE_HOME but found no luck in connecting to oracle database.

Thank you!

You may see different results when you use a particular Oracle client for the first time since Toad started vs ending connections in Toad and then making a new connection with a different Oracle client. The latter doesn't always work correctly.

Do you see different behavior in Toad 13.3 or just the beta? If both, then something changed on your PC. Toad 13.3 and 14.x do not share any settings.

As far as I know, nothing changed in the most recent beta regarding Oracle clients.

As soon as Beta got updated, I cannot connect to Database from both Toad versions(13.3 and 14) , So I uninstalled both versions and installed 13.2 still I receive same error.

Toad 14 beta cannot affect 13.3 or 13.2. Something else must have changed at the same time.

Possibly related: Toad 13.2 and prior will give an "Invalid Oracle Home" message if instant client files has the DLLs in a subfolder named "bin" (this is not the default configuration)

Note: There may be some junk in the registry that needs to be cleaned out after deinstall. See Cannot load OCI: C:\Oracle\product\12.2.0\client_1\BIN\OCI.dll

Info: After I uninstalled, installed oracle client, Toad is connecting to oracle database.

1 Like