HttpError 403 when requesting https://www.googleapis.com/discovery/v1/apis/gmail/v1/rest returned "The caller does not have permission"

Question

I have been using Gmail API to automatic email processing in production for many months now. All of a sudden since July 2, 2020 seeing the error message trying to access Gmail API.

HttpError 403 when requesting https://www.googleapis.com/discovery/v1/apis/gmail/v1/rest returned "The caller does not have permission"

Checked Gmail Dashboard and the credentials are active noting was removed or modified.

Checked code and can confirm nothing changed for 3-4 months.

And we are not using old token. Our code takes care of expired credentials and does a token refresh.

Also tried removing the token.pickle file, when rerun re-authenticated using the Gmail Auth screen and token.pickle file is recreated however the error message cannot be resolved.

It looks like something changed in Google's end.

Can someone please confirm ?

When doing a search seems lot of ppl are seeing this in various APIs recently but no viable solution is provided.

Answer 1

This is a system-wide issue on Google's side: https://issuetracker.google.com/issues/160441983