Google Analytics - getting an 'access token' using a 'refresh token'

• http://stackoverflow.com/questions/18820302/using-refresh-token-for-google-oauth-2-0-returns-http-400-bad-request
• http://stackoverflow.com/questions/10576386/invalid-grant-trying-to-get-oauth-token-from-google
• https://groups.google.com/forum/#!topic/google-analytics-data-export-api/4uNaJtquxCs

I was getting a 'invalid_grant' error, when I was trying to get a new access_token using a refresh_token.

In our case the problem was (probably) the following:

There are limits on the number of refresh-tokens that are given by google. 

I think, using our client_id, we had made too many requests for new refresh-tokens. So we probably crossed our limit. 

I reset my client-id, and then tried again, getting a 200 OK response with an access token in the payload.