I just tested the old example file I developed and posted above to check if perhaps the API implementation broke or something. It still works on my system, so I assume the issue might be on the Google authorization side (i.e. the Credential output might be incorrect):
200310_DotNET_GoogleAPIs_Sheet_MWT_00 (1).gh (15.7 KB)
And here’s my dependency setup (i.e. the compiled .dll files from 2020 and their location, plus the client_secret.json file that you must provide yourself):
Dependencies.zip (388.4 KB)