Social network Facebook has implemented a new API version 2.4, which amended the authorization of users on the sites. When creating new applications in this social network, they automatically receive this version of the API, whereby it was not possible to use authorization on your sites with Facebook, because e-mail address was not available.
To fix this problem you need to open a file engine/classes/social.class.php
find in it:
$params = array('access_token' => $token['access_token']);
The distribution on our server updated.
$params = array('access_token' => $token['access_token'], 'fields' => "id,name,email,first_name,last_name");