Why does not the Application_Start() event fire when I debug my ASP.NET MVC app?

asp.net-mvc debugging compilation
Tomas Aschan picture Tomas Aschan · Jun 9, 2009 · Viewed 49.2k times · Source

I currently have the following routines in my Global.asax.cs file:

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    routes.MapRoute(
        "Default",                                          
        "{controller}/{action}/{id}",                       
        new { controller = "Arrangement", action = "Index", id = "" }
    );
}

protected void Application_Start()
{
    RegisterRoutes(RouteTable.Routes);
    // Debugs the routes with Phil Haacks routing debugger (link below)
    RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes);
}

Routing debugger...

When I hit F5, the application fires up and unless I have a view named Index.aspx in the ~/Views/Home/ folder, I get the "View missing" error message, although I have re-defined the default route and removed the HomeController. I would expect to get the routing debugger, and if not that at least a request for ~/Views/Arrangement/Index.aspx.
A breakpoint on RegisterRoutes(Routetable.Routes); is never hit when debugging.

I have tried building, rebuilding, restarting VS, cleaning, rebuilding again etc, but nothing seems to work. Why doesn't the application run the current version of the code?

Answer

Vishal Seth picture Vishal Seth · Dec 2, 2010

I found the following answer on forums.asp.net:

Are you using IIS7 as the server or the built-in web server? I noticed when using IIS7 that if you start the debugger, let a page come up, then change Global.asax (the markup file, not code-behind) while the debugger is still running, then refresh the page, breakpoints in Application_Start will be hit.

I think what's happening is that pressing "play", VS just fires up the process, then attaches to it, but by the time it attaches to it the start event has already run. By changing Global.asax, you cause the app to restart and since the debugger's already attached you can hit the breakpoint. Not a great solution, but it seems to work.

Thats's what was happening in my case.

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