title: Google Cloud - oauth2client.client.HttpAccessTokenRefreshError: invalid_grant
body: <p>I got this error message when trying to execute Google Prediction API.</p>
  
  <pre><code>raise HttpAccessTokenRefreshError(error_msg, status=resp.status)
  oauth2client.client.HttpAccessTokenRefreshError: invalid_grant
  </code></pre>
  
  <p>My credential details</p>
  
  <pre><code>{
      "scopes": [],
      "private_key": "XXXXX",
      "id_token": null,
      "token_uri": "https://accounts.google.com/o/oauth2/token",
      "token_info_uri": null,
      "token_response": null,
      "client_id": null,
      "scope": "https://www.googleapis.com/auth/prediction https://www.googleapis.com/auth/devstorage.read_only",
      "token_expiry": null,
      "_class": "SignedJwtAssertionCredentials",
      "refresh_token": null,
      "_module": "oauth2client.client",
      "private_key_password": "notasecret",
      "access_token": null,
      "service_account_name": "account-1@myapp-1136.iam.gserviceaccount.com",
      "invalid": false,
      "assertion_type": null,
      "kwargs": {},
      "client_secret": null,
      "revoke_uri": "https://accounts.google.com/o/oauth2/revoke",
      "user_agent": null
  }
  </code></pre>