Google OAuth 2 Error 400: redirect_uri_mismatch but redirect uri is compliant and already registered in Google Cloud Console

[Nicholas Sliter]

Does anyone have a solution to a redurect_uri_mismatch when the redirect uri is already registered in GCP?

I am unable to use Oauth 2 on an internal app hosted on Heroku as I get a 400 error. 

More information here: https://stackoverflow.com/questions/71462058/q-google-oauth-2-error-400-redirect-uri-mismatch-but-redirect-uri-is-compliant

[George (Cloud Platform Support)]

Hello, 

How did you register the redirect URI? Setting a redirect URI in Cloud Console is not the proper course of action. You may check this answer to the "Google OAUTH: The redirect URI in the request did not match a registered redirect URI" question in stackoverflow. 

[Nicholas Sliter]

It is registered in my app.  Here is an example of a url encoded uri in a network request from my app to google oauth:  redirect_uri=https%3A%2F%2Fmiddcourses2.herokuapp.com%2Fapi%2Fauth%2Fcallback%2Fgoogle

[David Charles Martinez]

Hello, I see you have solved this issue by updating your client ID and client secret. Posting this in here so it will be helpful for other users having the same issue.