The following code works just fine without FriendlyUrls turned on for an ASP.Net Web Forms project:
public static class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
var settings = new FriendlyUrlSettings();
//Esta wea se deshabilita para que funcione ajax autocomplete.
//settings.AutoRedirectMode = RedirectMode.Permanent;
settings.AutoRedirectMode = RedirectMode.Off;
routes.EnableFriendlyUrls(settings);
}
}