The resource cannot be found ( controller action MVC 5, .NET 4.6.1) - asp.net-mvc-routing

Question

I am trying to download a file, when I click on a hyperlink, but I always get a Resource not found exception.
The controller action never gets hit.
Index.cs.html:
#{
ViewBag.Title = "Files";
}
#Html.ActionLink("Download Report", "DownloadFile", "FileDownload", new { type = "pdf" }, new { #class = "" })
Rendered Action-Link:
http://localhost:58255/FileDownload/DownloadFile?type=pdf
When I uncomment the MapRoute entry "Files" in the routeConfig the action link is rendered like this:
http://localhost:58255/FileDownload/DownloadFile/pdf
But neither of them work! -> The resource cannot be found
Controller (Only Index action gets hit when the view loads, but nothing when I click on the actionlink):
[AllowAnonymous]
public class FileDownloadController : Controller
{
public ActionResult Index()
{
return View();
}
FilePathResult DownloadFile(string type)
{
var fn = $"~/Documents/Test.{type}";
return File(fn, "application/pdf", Server.UrlEncode(fn));
}
RegisterRoutes.cs:
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapMvcAttributeRoutes(); // for attribute routing on action
AreaRegistration.RegisterAllAreas();
//routes.MapRoute(
// name: "Files",
// url: "{controller}/{action}/{type}",
// defaults: new { controller = "FileDownload", action = "DownloadFile", type = UrlParameter.Optional }
//);
// Should be last
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional });
}
...coming from the WebForms area...

Answer 1

Please try to add public access modifier before action name
public FilePathResult DownloadFile(string type)
{
var fn = $"~/Documents/Test.{type}";
return File(fn, "application/pdf", Server.UrlEncode(fn));
}