ASP.NET Custom error page for 404 returns 302 for http status

In my asp.net web site I have custom error pages defined as following in my web.config file.

<customErrors mode="On" defaultRedirect="~/defaulterror.htm" >
<error statusCode="404" redirect="~/404.htm" />

When file is not found it correctly display 404.htm page but the issue is when I do Fiddler trace it returns 302 as HTTP status code开发者_开发技巧.This is a big issue for search engine page indexing due to this lot of broken links still have been indexed recently because of this in my web site. how can I prevent returning 302 as HTTP status code for file not found errors and return 404 for file not found errors.I am using asp.net 3.5.

After Googling about this issue, it seems that this is the default behavior that Microsoft ASP.NET provides for the situation. This is very bad for SEO. A work around I found is to check whether the requested file exists in an HTTP handler (or global.asax file), or use:

<customErrors mode="On" redirectMode="ResponseRewrite">
    <error statusCode="404" redirect="/FileNotFound.aspx" />
</customErrors>

If the requested file does not exist, then rewrite the request path to a file not found page (if using an HTTP handler or global.asax), clear the server errors on the 404 error page code behind, and add a 404 error header to the response manually rather than waiting for server to do so.

Server.ClearError();
Response.Status = "404 Not Found";
Response.StatusCode = 404;

In ASP.NET 4.0 you can use redirectMode="ResponseRewrite" to send nice error pages and the proper HTTP code.

As you probably already know the 302 response is used to advise the caller that the requested resource has been moved to a different location.

When you see, in Fiddler, the 302 http code being returned is there also a 'location' declaration in the header? For example:

HTTP/1.1 302 Found
Location: http://www.yoursite.com/somewhere/blah.htm

It seems that you may have 'something' on the webserver that is intercepting the 404 returns and replacing these with 302's. I know this isn't much to go on but I would suggest that you look at the IIS configuration for the site.

If you add the following to your 404 page code behind. You will get the correct results -

Page 404.aspx

protected void Page_Load(object sender, EventArgs e)
{
    Response.StatusCode = 404;
}

The solution was even simpler.. Please check out my response over here: http://blog.hebbink.com/post/2010/12/14/NET-custom-404-error-page-returns-302-for-http-status.aspx