It looks like your .aspx lives in the same directory as your Razor-driven application. The easiest way to skin this cat is to modify your App_Start/RouteConfig.cs file.
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.IgnoreRoute("{*allaspx}", new {allaspx=@".*\.aspx(/.*)?"});
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
This should allow the page to load without the MVC application trying to parse it.