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I'm having a weird problem with one of my IIS 7.5 boxes. One of my coworkers rebooted the primary domain controller and after it came backup the IIS box started give out 503 errors. I restarted IIS and it didn't help, rebooting the box did take care of it. The application is a application.

There was nothing in the event log that I could see, in the httperr log there were lines like:

 2011-12-07 15:03:47 8677 80 HTTP/1.1 GET / 503 1 AppOffline

My question is: why did IIS go down, and what can I do to protect it from going down?

Thanks for your help.


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up vote 1 down vote accepted

From technet 943891

503.0 - Service unavailable. The request is sent to an application pool that is currently stopped or that is currently disabled. To resolve this issue, make sure that the destination application pool is started. The event log may give information about why the application pool is stopped or disabled.

I would perform the exact step as mentioned in the article to see what's going wrong with the appPool. Verify if the appPool identity is a domain account and then the account password is correct.

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I had a background thread that crashed since dns was down when the domain controller rebooted, and took out the app pool. Thanks for pointing me in the right direction. – Jbecwar Dec 7 '11 at 17:57

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