ASP.NET MVC CustomErrors

badrequest.cshtml

@{
    ViewBag.Title = "Error";
}
<h1>Looks like something went wrong.</h1>
<p>Sorry, there was an error in your request.</p>

ErrorController.cs

public class ErrorController : Controller
{
    // GET: Error
    public ActionResult Index()
    {
        //Deal with aspxerrorpath
        if (!string.IsNullOrEmpty(Request.QueryString["aspxerrorpath"]))
        {
            return RedirectToAction("Index");
        }
        else
        {
            return View();
        }
    }
    // GET: PageNotFound
    public ActionResult PageNotFound()
    {
        //Deal with aspxerrorpath
        if (!string.IsNullOrEmpty(Request.QueryString["aspxerrorpath"]))
        {
           return RedirectToAction("PageNotFound");
        }
        else
        {
            //Setting the Response.StatusCode to 404 causes a conflict on Azure
            //Response.StatusCode = 404;  //you may want to set this to 200

            return View();
        }
    }
    // GET: BadRequest
    public ActionResult BadRequest()
    {
        //Deal with aspxerrorpath
        if (!string.IsNullOrEmpty(Request.QueryString["aspxerrorpath"]))
        {
            return RedirectToAction("BadRequest");
        }
        else
        {
            // Fix to deal with Bad Requests.
            // The requested outcome would is that if a 400 error was thrown it wouldn't display the YSOD but instead a friendly error page.
            // Which adding existingResponse="Replace" will handle which is good for when dealing with exceptions thrown due to a "potentially dangerous request value".
            // However if the code returns a 400 status code for example which would be picked up in a json call - instead of returning the 400 and letting it get handled by the client,
            // it get's hijack the response and throw an error page which results in a status code of 200 which means the client views it as a success.
            // By setting the response code here it will allow to status code to be returned to the client and still serve the friendly error page.
            Response.StatusCode = 400;
            Response.StatusDescription = "Bad Request";
            //In some cases you may need to uncomment the line below with TrySkipIisCustomErrors
            //Response.TrySkipIisCustomErrors = true;
            return View();
        }
    }
}

index.cshtml

@{
    ViewBag.Title = "Error";
}
<h1>Looks like something went wrong.</h1>
<p>Sorry, we are experiencing technical difficulties. We are working on getting this problem resolved. Sorry for any inconvenience!</p>

PageNotFound.cshtml

@{
    ViewBag.Title = "Page Not Found";
}
<h1>Page Not Found</h1>
<p>The page that you have requested doesn&rsquo;t exist or has been removed from our Web site. We&rsquo;ve recently updated our site so the page you&rsquo;re looking for might have been removed.</p>

<p>If you entered the Web page address yourself, please make sure that you entered the correct spelling.</p>

web.config

<configuration>
    <system.web>
        <customErrors mode="On" defaultRedirect="~/Error" redirectMode="ResponseRedirect">
          <error statusCode="404" redirect="~/Error/PageNotFound" />
        </customErrors>
    </system.web>
    <system.webServer>
        <httpErrors errorMode="Custom" existingResponse="Replace">
            <clear />
            <error statusCode="400" responseMode="ExecuteURL" path="/Error/BadRequest"/>
            <error statusCode="404" responseMode="ExecuteURL" path="/Error/PageNotFound"/>
            <error statusCode="500" responseMode="ExecuteURL" path="/Error"/>
        </httpErrors>
    </system.webServer>
</configuration>