Custom error pages with HandleError attribute

Question

I have asp.net web application and try to specify custom HTML for Dynamic Ip Restrictions module, which returns 401 prior to .net code.

I've added following to my web.config:

<httpErrors>
  <remove statusCode="404" subStatusCode="-1" />
  <remove statusCode="401" subStatusCode="-1" />
  <error statusCode="401" path="ddos.html" responseMode="File" />
  <error statusCode="401" subStatusCode="502" path="ddos.html" responseMode="File" />
  <error statusCode="404" prefixLanguageFilePath="" path="/404" responseMode="ExecuteURL" />
</httpErrors>

Productin environment (windows Server 2008): Pages with 404 and 401 works fine, but exception handling is broken - i see built-in iis "red" page instead of custom page.

Development environment (windows 7/8): 404 and erors are fine, but 401 redirect user to login page.

Exception handling defined as:

[HandleError(View = "Error", Master = "~/Views/Shared/_ThreeColumnsLayout.cshtml")]

UPD1: Also, I can add that if I remove pages with code 500, I see foloowing plain text message:

The page cannot be displayed because an internal server error has occurred.

Answer 1

<httpErrors existingResponse="Auto">

does the trick