Upgrade to MVC3. ashx resource cannot be found. Routing issue?

Question

I have searched high and low for a solution to this problem and have not found one. I just upgraded a MVC2 application to MVC3 using this guide: http://www.asp.net/whitepapers/mvc3-release-notes#upgrading

I also upgraded the project from VS2008 to VS2012. IIS 7.5

Everything went flawlessly except my Preview.ashx is now giving me resource not found. This page is supposed to display a preview image when called with a url in the query string. I tried changing routes, checking the controller names, setting Specific Page in the Web settings, etc. I am pretty sure it has something to do with the routes or some setting that got screwed up during the upgrade, but I cannot figure it out.

I have the site setup using a virtual directory in IIS at http://localhost/comm

EDIT: I just rebuilt the site using a fresh installation of MVC3 and the problem still exists. After rebuilding the site I realized that there are .aspx files in the same directory that work fine. It is only .ashx files that are not routing correctly.

Global.asax

public static void RegisterRoutes(RouteCollection routes) {
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    routes.IgnoreRoute("{resource}.aspx/{*pathInfo}");
    routes.IgnoreRoute("{resource}.ashx/{*pathInfo}");

    routes.MapRoute(
        "Default", // Route name
        "{instance}/{controller}/{action}/{id}", // URL with parameters
        new { instance = "demo", controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
        );

    }

    protected void Application_Start() {
            AreaRegistration.RegisterAllAreas();
            RegisterRoutes(RouteTable.Routes);
    }

Error

The resource cannot be found.

Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable.  Please review the following URL and make sure that it is spelled correctly. 

Requested URL: /comm/Views/Review/FileViewer.ashx

Answer 1

I gave up trying to get the ashx to work and ended up just building a FilesResult action in the controller that returns the image. The ashx was receiving an HttpContext in order to process the image and return it. I created an action that takes a path, performs its work, and returns the image. There is something wonky about .ashx files and MVC routing that I could not figure out. None of my ashx files are working, but they can all be rebuilt as actions so I guess its not a big deal. Below is the action that replaces the Preview.ashx

public FileResult Preview(string path) {
// Database fetch of image details
try {
    // Get the relative path
    if (!path.IsNull()) {
        // Get the path
        string filePath = path;
        string absolutePath = ...

        // Make sure the the file exists
        if (System.IO.File.Exists(absolutePath)) {
            // Check the preview
            string previewPath = ...;

            // Has preview
            bool hasPreview = true;
            // Check to see if the preview exists
            if (!System.IO.File.Exists(previewPath) || System.IO.File.GetLastWriteTime(previewPath) < System.IO.File.GetLastWriteTime(absolutePath)) {
                try {
                    // Generate preview
                    hasPreview = ...  != null;
                }
                catch (Exception exc) {
                    hasPreview = false;
                }
            }

            // Once the path is handled, set the type
            if (hasPreview) {
                return new FileStreamResult(new FileStream(previewPath, FileMode.Open), "image/png");
            }
            // No preview
            else
                return WriteDefault();
        }
        else
            // Write the default (blank)
            return WriteDefault();
    }
    else {
        return WriteDefault();
    }
}
catch {
    // Write the default (no_photo)
    return WriteDefault();
    }
}

private FileContentResult WriteDefault() {
    // Write the default
    System.Drawing.Bitmap bmp = new Bitmap(25, 25);
    System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bmp);
    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    g.FillRectangle(System.Drawing.Brushes.White, 0, 0, 25, 25);
    bmp = new Bitmap(25, 25, g);
    MemoryStream str = new MemoryStream();
    bmp.Save(str, ImageFormat.Png);
    return File(str.ToArray(), "image/png");
}