Steps to Reproduce On your Windows Phone, Go to any URL which needs visitor to be logged in. For a private forum, this would be any page. For xenforo.com for instance, this page http://xenforo.com/community/forums/bugs/create-thread needs you to be logged in. You will see a 403 Forbidden Error. This is because in XenForo_ControllerPublic_Error, on line 87, the HTTP header response code is being set to 403: PHP: $view->responseCode = 403; Windows Phone stops dead in it's track as soon as it receives the 403 Forbidden error response, thereby not showing the Login page and not giving the user the opportunity to Login.