Without seeing the full error message that being
Invalid_grant {Message here}
It is hard to help but from my experience is most often caused by one of the following.
Refresh token expire, app not in production.
There are serval reasons why a refresh token can expire the most common one currently is as follows.
A Google Cloud Platform project with an OAuth consent screen configured for an
external user type and a publishing status of "Testing" is issued a refresh token expiring in 7 days.
The fix is to go to google developer console on the consent screen and set your application to production, then your refresh token will stop expiring.
invalid_grant: Invalid JWT
{ “error”: “invalid_grant”, “error_description”: “Invalid JWT: Token must be a short-lived token (60 minutes) and in a reasonable timeframe. Check your iat and exp values and use a clock with skew to account for clock differences between systems.” }
Your server’s clock is not in sync with NTP. (Solution: check the server time if its incorrect fix it. )
invalid_grant: Code was already redeemed
Means that you are taking an authentication code that has already been used and trying to get another access token / refresh token for it. Authentication code can only be used once and they do expire so they need to be used quickly.
Invalid_grant: bad request
Normally means that the client id and secrete you are using to refresh the access token. Was not the one that was use to create the refresh token you are using.
Always store most recent refresh token.
Remember to always store the most recent refresh token. You can only have 50 out standing refresh tokens for a single user and the oldest one will expire. Depending upon the language you are using a new refresh token may be returned to you upon a refresh of the access token. Also if you request consent of the user more then once you will get a different refresh token.
User revoked access
If the user revoked your access in their google account, your refresh token will no longer work.
user changed password with gmail scope.
If your refresh token was created with a gmail scope and the user changed their password. your refresh token will be expired.
Links
Oauth2 Rfc docs for invalid_grant error rfc6749
invalid_grant
The provided authorization grant (e.g., authorization
code, resource owner credentials) or refresh token is
invalid, expired, revoked, does not match the redirection
URI used in the authorization request, or was issued to
another client.