ASP.NET MVC 5 Custom Error Page

I am using a custom authorize attribute in a ASP.NET MVC 5 application like following:

public class CustomAuthorizeAttribute : AuthorizeAttribute
{
    protected override void HandleUnauthorizedRequest(AuthorizationContext context)
    {
        if (context.HttpContext.Request.IsAuthenticated)
        {
            context.Result = new System.Web.Mvc.HttpStatusCodeResult((int)System.Net.HttpStatusCode.Forbidden);                
        }
        else
        {
            base.HandleUnauthorizedRequest(context);
        }
    }
}

In system.web section of my web.config I mentioned error paths like:

<system.web>
    <customErrors mode="On" defaultRedirect="/Error/Error">
      <error statusCode="403" redirect="/Error/NoPermissions"/>
    </customErrors>
</system.web>

But I am never redirected to my custom error page at /Error/NoPermissions. Instead the browser display the general error page saying "HTTP Error 403.0 - Forbidden".

Thanks everyone, but problem is not with 403 code. Actually the problem was with the way i was trying to return 403. I just changed my code to throw an HttpException instead of returning the HttpStatusCodeResult and every things works now. I can return any HTTP status code by throwing HttpException exception and my customErrors configuration catches all of them. May be HttpStatusCodeResult is not doing the exact job I expected it to do.

I just replaced

context.Result = new System.Web.Mvc.HttpStatusCodeResult((int)System.Net.HttpStatusCode.Forbidden);

with

throw new HttpException((int)System.Net.HttpStatusCode.Forbidden, "Forbidden");

That's it.

Happy coding.