got 'invalid_grant' in oauth2 SignedJwtAssertionCredentials

Question

I am trying to make an oauth2 access_token in a server-to-server JSON API scenario. But it failed with invalid_grant error, please help.

from oauth2client.client import SignedJwtAssertionCredentials

KEY_FILE = 'xxxxxxxxxxxx-privatekey.p12'

with open(KEY_FILE, 'r') as fd:
    key = fd.read()

SERVICE_ACCOUNT_EMAIL = 'xxxxxx.apps.googleusercontent.com'

credentials = SignedJwtAssertionCredentials(SERVICE_ACCOUNT_EMAIL, key,
      scope="https://www.googleapis.com/auth/datastore https://www.googleapis.com/auth/userinfo.email",
      token_uri='https://accounts.google.com/o/oauth2/token')


assertion = credentials._generate_assertion()

h = httplib2.Http()
credentials._do_refresh_request(h.request)

and I got

Traceback (most recent call last):
  File "/Users/pahud/Projects/oauth2client/x.py", line 24, in <module>
    credentials._do_refresh_request(h.request)
  File "/Users/pahud/Projects/oauth2client/oauth2client/client.py", line 710, in _do_refresh_request
    raise AccessTokenRefreshError(error_msg)
oauth2client.client.AccessTokenRefreshError: invalid_grant
[Finished in 0.7s with exit code 1]

http://i.stack.imgur.com/iGGYx.png

Answer 1

I fixed it.

SERVICE_ACCOUNT_EMAIL = 'xxxxxx.apps.googleusercontent.com'

the above is client ID not Email, I fixed this and it's working now.