ORA-01017 for PROXY log on WITHOUT Oracle Client

HI I am using Toad for Oracle 16.0.90. 1509 WITHOUT an Oracle Client. I am using the tnsname.ora in the same directory as toad.exe. Oracle DB 19C.

I am able to log into my user account without errors.
When I attempt to PROXY log on using format user[proxyuser] it throws an ORA-01017 error.

I've tried wrapping the whole string with single quotes, double quotes, escaping the brackets. nothing works.

Anyone have any ideas?

Sorry, Proxy connections require an Oracle client.

Toad 16.2 and newer will give you a nice message saying this if you attempt to connect by proxy. Older versions just give the ORA-01017 as you found.