Google Code-in

It's supposed that once the user enters their login data (his mail address and his password), Gmail activity should generate automatically a credentials file, but for some reason some people are having problems with that (apparently the credentials file is never created).

Note: It's very probable the problem is on login_screen.py -> _load_finished_cb, but it's important to keep in mind that some users can login with that code, so it can't be completely replaced.

In any case, you must research about this error and then fix it.