Mysterious IIS Problem: Site stops serving dynamic pages, no errors in logs

Question

Hi all,

This may be the most mysterious problem I've ever encountered.

We have an IIS7 install with 3 Web Sites on it, each with it's own Application Pool. Once a day, for about an hour, a specific one of them goes down.

What I mean by "goes down" is:

1. It stops responding to requests for dynamic pages (ex. default.aspx) but will serve static files fine (logo.png).
2. Wireshark tells me that these dynamic page requests are actually return HTTP 500 Internal Server errors, but in the browser, I don't see an error. I just see the browser spinning.
3. If I log on locally to the box and surf around everything runs fine. All the pages pull up, so the database is being queried. It all seems perfectly normal.
4. There are no errors in the event log.
5. There are no errors recorded that have been captured by our internal (Application-level) error logging.
6. The basic IIS log file, which I thought logged every request, shows no record of these requests coming in.

And, if I restart the App Pool for the Web Site, everything comes back immediately. Or, if I just wait an hour or so, it comes back.

So, I've ruled out:

1. DNS issues, since I have no problem terminal servicing into the box by hostname.
2. Database issues, since the site works fine when I'm local to the box and surfing around
3. HTTP firewall issues, since I'm seeing the requests in wireshark, and am even getting images to serve up.

I have to assume it's a problem with my application, but IIS doesn't even show that these requests ever happened, and nothing in IIS or my app is logging errors.

It also doesn't even go down at the same time each day. This started at night (@midnight) and seems that it's gradually started moving it's daily time by an hour or so, until the point now where it hit at 9AM.

Any clues you might have for further troubleshooting would be greatly appreciated.

Tom

Answer 1

I'd fire up performance monitor and look for requests and exceptions being thrown. Not a whole lot of value in my answer but it might started pointing you in the right direction.

Actually, check the event logs first, see if something is throwing errors. Also, check memory usage and paging.

Answer 2

Did you ever figure out this issue? We're experiencing exactly the same symptoms, except we're on IIS 6.

Thanks,

Ming

Answer 3

I'm having the same problem, this article http://blogs.msdn.com/david.wang/archive/2005/09/21/HOWTO%5FDiagnose%5FIIS6%5Ffailing%5Fto%5Faccept%5Fconnections%5Fdue%5Fto%5FConnections%5FRefused.aspx

describes a possible cause/solution, i think that's the problem we are having.

Answer 4

i am also having same problem

and i need solution :(