Checklist

• I have verified that that issue exists against the master branch of Django REST framework.
• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• This is not a usage question. (Those should be directed to the discussion group instead.)
• This cannot be dealt with as a third party library. (We prefer new functionality to be in the form of third party libraries where possible.)
• I have reduced the issue to the simplest possible case.
• I have included a failing test as a pull request. (If you are unable to do so we can still accept the issue.)

Steps to reproduce

Make an Authentication class:

class AttributeErrorAuthentication(BaseAuthentication):
    def authenticate(self, request):
        raise AttributeError
    
    def authenticate_header(self, request):
        return 'NotImportant'

Set it in DEFAULT_AUTHENTICATION_CLASSES setting:

REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'api.authentication.AttributeErrorAuthentication',
    )
}

Make a simple view:

class UserView(generics.CreateAPIView, generics.RetrieveAPIView, generics.UpdateAPIView):
    serializer_class = UserSerializer

    def get_object(self):
        return self.request.user

Include an empty DefaultRouter and the UserView in the same urlpatterns :

router = DefaultRouter()
urlpatterns = [
    url(r'^', include(router.urls)),
    url(r'^user/$', views.UserView.as_view(), name='user-detail'),
]

or register something on it, doesn't matter I think.

Make a request to http://localhost:8000/api/.

Expected behavior

Show AttributeError traceback, HTTP 500 server error

Actual behavior

No traceback, HTTP 200 OK response.

On the /user/ endpoint I got a traceback, but on api_root, nothing.