title: Social-auth AuthCanceled error after redirect from facebook
body: <p>I've set up <code>social-auth-app-django</code> in production. But after facebook redirect I got <code>AuthCanceled</code> and still unable to get it work. </p>
  
  <p>In my user model email address used to sign up. This is my user model:</p>
  
  <pre><code>class User(AbstractUser):
      email = models.EmailField(_('email address'), unique=True)
      avatar = models.ImageField(blank=True)
  
      USERNAME_FIELD = 'email'
      REQUIRED_FIELDS = ['username']
  </code></pre>
  
  <p>in settings.py:</p>
  
  <pre><code>MIDDLEWARE = [
      ...
      'social_django.middleware.SocialAuthExceptionMiddleware',
  ]
  
  TEMPLATES = [
      ...
          'context_processors': [
              ...
              'social_django.context_processors.backends',
              'social_django.context_processors.login_redirect',
      ],
  ]
  
  AUTHENTICATION_BACKENDS = (
      'social_core.backends.facebook.FacebookOAuth2',
      'accounts.backends.ModelBackend'
  )
  
  LOGIN_URL = '/'
  LOGOUT_URL = '/'
  LOGIN_REDIRECT_URL = '/'
  LOGOUT_REDIRECT_URL = '/'
  
  SOCIAL_AUTH_FACEBOOK_KEY = '..'  # App ID
  SOCIAL_AUTH_FACEBOOK_SECRET = '...'  # App Secret
  SOCIAL_AUTH_FACEBOOK_SCOPE = ['email']
  SOCIAL_AUTH_FACEBOOK_PROFILE_EXTRA_PARAMS = {
      'fields': 'id,name,email',
  }
  
  SOCIAL_AUTH_PIPELINE = (
      'social_core.pipeline.social_auth.social_details',
      'social_core.pipeline.social_auth.social_uid',
      'social_core.pipeline.social_auth.auth_allowed',
      'social_core.pipeline.social_auth.social_user',
      'social_core.pipeline.user.get_username',
      'social_core.pipeline.user.create_user',
      'social_core.pipeline.social_auth.associate_user',
      'social_core.pipeline.social_auth.load_extra_data',
      'social_core.pipeline.user.user_details',
  )
  </code></pre>
  
  <p>Valid OAuth redirect URIs in facebook login app: <code>https://example.com/oauth/complete/facebook/</code></p>
  
  <p>Thank you for your time and help.</p>