post https://api.pandadoc.com/oauth2/access_token/
Eventually, access_token expires and accessing an API method returns 401 unauthorized. Your application needs to refresh the OAuth2 token with the stored refresh_token returned when initially creating an access token.
Once refreshed, calls on behalf of the originally authorized user can resume immediately. Use the newly returned access_token for all future API requests.
Invalid Grant?
If you receive an
invalid grantresponse, it is likely because yourrefresh_tokenis invalid.