Unable to refresh access token : response is “unauthorized_client”

Question

I am getting an error when I try to refresh access token:

400 Bad Request

{error : \"unauthorized_client\"}

From

Answer 1

PROBLEM EXPLANATION

With the hint @MartinV gave I was finally able to fix it! Because his answer doesn't explain very well how to solve it, I'm going to post it here.

The problem is because we all have generated the Refresh Token using Google's OAuth Playground, but when you click 'Authorize APIs' in the first step, it takes you to the concent screen using the Playground app. After that, all the tokens that you create can be used only by the Playground app, but of course you don't know either the Client ID or the Client Secret for that app.

SOLUTION

The solution is to make Playground to use your own Client ID and Secret. To do so, click on the Settings button:

And enter your Client ID and Secret. But, before you do that, as it says there, you need to go to the Developer's Console, find your OAuth 2.0 client IDs client, edit it and add https://developers.google.com/oauthplayground under Authorized redirect URIs. After you added that and saved the changes, go back to the playground and try to Authorize APIs. In my case it took like 15 minutes before the changes in the Authorized redirect URIs took effect.

Once you're done, don't forget to remove the Playground URI from the Developer Console!

EXTRA

Once I have done that, in Python I did this and it worked:

access_token = None 
client_id = 'xxxxxxxx.apps.googleusercontent.com'
client_secret = 'xxxxxxxxxxxx'
refresh_token = 'xxxxxxxxxxxx'
token_expiry = None
token_uri = "https://accounts.google.com/o/oauth2/token"
user_agent = 'YourAgent/1.0'

credentials = client.GoogleCredentials(access_token, client_id, client_secret, refresh_token, token_expiry, token_uri, user_agent)

http = credentials.authorize(httplib2.Http())
credentials.refresh(http)

service = build('drive', 'v3', http=http)
req = service.files().list()
resp = req.execute(http=http)