How can I Handler 404 errors without the framework throwing an Exception 500 error code?
http://jason.whitehorn.ws/2008/06/17/Friendly-404-Errors-In-ASPNET-MVC.aspx gives the following explanation:
Add a wildcard routing rule as your final rule:
routes.MapRoute("Error",
"{*url}",
new { controller = "Error", action = "Http404" });
Any request that doesn't match another rule gets routed to the Http404 action of the Error controller, which you also need to configure:
public ActionResult Http404(string url) {
Response.StatusCode = 404;
ViewData["url"] = url;
return View();
}