As of May 2015, Google are no longer supporting the Open Auth 2.0 framework, which is used by SMB and other platforms to provide a single sign on capability for accessing the system.
Google have announced a new authentication tool which will provide the same function. We have completed integration with this new system and, as a consequence, you will need to re-authenticate your account to continue to sign in with Google.
To do this, log into SMB with your SMB username and password. Then, once in the system, open the user menu in the top right corner of the page by clicking on your name, then select "My Settings" to open your personal settings page. At the bottom of this page, use the form provided to reconnect your SMB account with your Google account. You will now be able to sign in through Google as before.