If you visit a URL that requires authentication but are not authenticated, Circle shows a 404 error page. This is confusing (particularly in an enterprise installation) because it is not obvious that you need to log in and people may think that the link they followed is incorrect.
Circle should redirect to the login page and then return to the target page after authentication, showing an error only if the page actually does not exist or the user does not have permission.
CCI-I-459