RE: Toad Data Point 3.8.1.677 / Windows 10 - Unable to Connect to Oracle 12c Database - SEHException/Win32Exception

Oracle 12.1.0.2.0, 64-bit client.

I believe I found the cause of the problem. My system's ORACLE_HOME was set to the path of an earlier (also installed) version of the client:

C:\oracle\product\11.1.0.6

I changed this to the path of the 12c client:

C:\oracle\product\12.1.0.2

And now Toad connects as expected.

Thanks very much! Hopefully your tips and this information will help other Toad users.