How to pass-through custom content of an HTTP 401 in Azure?

Question

I have an application which provides custom content on HTTP 401. The authorization filter which inherits from AuthorizeAttribute contains a method like this:

protected override void HandleUnauthorizedRequest(
    AuthorizationContext filterContext)
{
    filterContext.HttpContext.Response.Clear();
    filterContext.HttpContext.Response.StatusCode =
        (int)HttpStatusCode.Unauthorized;
    filterContext.HttpContext.Response.Write("Custom content goes here.");
    filterContext.Result = new HttpUnauthorizedResult();
}

When running the application locally and hitting a protected resource, the custom content is displayed successfully.

Once deployed to Windows Azure, the application simply displays:

You do not have permission to view this directory or page.

The header is still correct HTTP/1.1 401 Unauthorized, but the content I've set is gone.

How to prevent Azure from interfering with my application and pass-through the content from Responde.Write through HTTP down to the client?

Answer 1

As with IIS, adding:

filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;

solves the issue. With this directive, the custom content is now shown to the client.