I came across this problem with a company's intranet that we run (powered by Wordpress) - it's got us all stumped.
When attempting to authenticate a user using the Google Contacts API, an error is returned after granting permission to access the user's contact list and before full authentication is given, but no details are given as to what the error actually is.
It was working absolutely fine until one day in late April/early May it suddenly stopped working.
We we're using the following scope: http://www.google.com/m8/feeds/contacts/default/full.
An interim solution has been put into place, using the Google+ API instead. This is working well, except that the API is not providing the user's email address after authenticating, only their profile details.
We absolutely need the email address in order to limit access to the website to people with certain email addresses, as well as intergrate properly with WordPress' user management, generating new user accounts and linking them to authenticated email addresses.
We'd really appreciate any help!