really odd one here.

I have a website which runs on IIS fine most of the time. On some occasions though I get a white 404 page with the text:

Not Found HTTP Error 404. The requested resource is not found.

Running fiddler I can see the following http headers:

HTTP/1.1 404 Not Found Content-Type: text/html; charset=us-ascii Server: Microsoft-HTTPAPI/2.0 Date: Thu, 10 Nov 2011 21:25:01 GMT Connection: close Content-Length: 315

So a "connection close" error seems to be happening intermittently.

A couple of refreshes later the page loads fine with the following headers:

HTTP/1.1 200 OK Content-Type: text/html Last-Modified: Thu, 10 Nov 2011 15:53:56 GMT Accept-Ranges: bytes ETag: "02d1f3c09fcc1:0" Server: Microsoft-IIS/7.5 X-Powered-By: ASP.NET mycustomheader: 01 Date: Thu, 10 Nov 2011 21:25:24 GMT Content-Length: 16307

I notice that the 404 header doesn't have custom http header response which I've added as part of my debug steps. In IIS if an error is being served by a specific web should it not have the custom header aswell?

Anyone know why certain http requests would intermittently be closed by IIS?



  • 1
    Did you ever get to the bottom of this?
    – Lloyd
    Jul 3, 2012 at 9:34
  • Would be nice to know if you came across a solution. I have a similar problem.
    – stoj
    Feb 4, 2013 at 18:00
  • what kind of content is this?
    – bkr
    May 30, 2014 at 4:38
  • Wow. This is old, and you probably don't care anymore. Anyhow, the problem isn't that the connection is being closed; that's just a 404 error. From your response headers, it's obvious that your code isn't even being touched. The response is coming from the lower-level HTTP subsystem; IIS isn't even getting to the Asp.Net pipeline. For whatever the reason, it's not finding your .aspx file. I would suggest you look at the filesystem/OS level for answers.
    – Granger
    Jul 11, 2014 at 15:48

1 Answer 1


Have a nice day.

Please, have a minute to check the next site. That's important to solve the problem, because you're not giving any Event Log details.

Let us know if this helps you to solve the problem. Thank you.


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    – HBruijn
    Sep 5, 2018 at 13:33

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