404 Custom Redirect

Hello I am trying to do a redirect if the response is a 404 but it is not working as expected, can you experts see the issue?. It still goes to the generic 404

in my Global.asax

protected void Appli开发者_C百科cation_BeginRequest(Object sender, EventArgs e)
{
       if (Response.Status == "404 Not Found")
        {
            string notFound = "~/custom_notfound.aspx";
            Response.Redirect(notFound);
        } 

}

UPDATE

Tried so far

(Response.Status == "404 Not Found")
(Response.Status == "404")
(Response.StatusCode == 404)

You can also use the web.config customerrors section - as shown here

e.g. In the system.web section,

<customErrors mode="On" defaultRedirect="/custom_error.aspx">
    <error statusCode="404" redirect="/custom_notfound.aspx" />
</customErrors>

I don't think BeginRequest could know about 404 errors. Try implementing Application_Error instead. Check to see if Server.GetLastError() is an HttpException, and if so, check the status.

You could add to your web.config to do this redirection, you don't need to use Application_BeginRequest to handle this.

See this ServerFault question.

If you can't use the web.config then I would set your startup page to one that doesn't exist, put a breakpoint in your BeginRequest, debug the app and look at the request to see how to determine it is a 404. That would be much easier to determine the optimal solution.

Looking into this some more, there is a HttpStatusCode that is used in the HttpWebResponse class. So it may make sense to use a different override of the Application to get the default response, and then check it's status against the Enum.

You can also use the web.config

<system.webServer>
  <httpErrors errorMode="Custom" defaultResponseMode="File" >
     <remove statusCode="404" />
     <remove statusCode="500" />
     <error statusCode="404" path="404.html" />
     <error statusCode="500" path="500.html" />
   </httpErrors>
</system.webServer>