How to implement proper HTTP error handling in .NET MVC 2?

Here’s one technique you could use. Define an ErrorsController which will serve the error pages:

public class ErrorsController : Controller
{
    public ActionResult Http404()
    {
        Response.StatusCode = 404;
        return Content("404", "text/plain");
    }

    public ActionResult Http500()
    {
        Response.StatusCode = 500;
        return Content("500", "text/plain");
    }

    public ActionResult Http403()
    {
        Response.StatusCode = 403;
        return Content("403", "text/plain");
    }
}

and then in Global.asax you could subscribe for the Application_Error event where you could log the exception and execute the corresponding action of the ErrorsController:

protected void Application_Error(object sender, EventArgs e)
{
    var app = (MvcApplication)sender;
    var context = app.Context;
    var ex = app.Server.GetLastError();
    context.Response.Clear();
    context.ClearError();
    var httpException = ex as HttpException;

    var routeData = new RouteData();
    routeData.Values["controller"] = "errors";
    routeData.Values["exception"] = ex;
    routeData.Values["action"] = "http500";
    if (httpException != null)
    {
        switch (httpException.GetHttpCode())
        {
            case 404:
                routeData.Values["action"] = "http404";
                break;
            case 403:
                routeData.Values["action"] = "http403";
                break;
            case 500:
                routeData.Values["action"] = "http500";
                break;
        }
    }
    IController controller = new ErrorsController();
    controller.Execute(new RequestContext(new HttpContextWrapper(context), routeData));
}

And now all that’s left is to start throwing proper exceptions:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        throw new HttpException(404, "NotFound");
    }
}