So here I am moving new ASP.NET 3.5 code from QA, where the small changes I made worked fine, to Production, where it fails and shows only "Service Unavailable" on the page. Nothing in the web log. Nothing in the Event Log. I've stopped and started the site, refreshed the web server, and I've even jumped up and down screaming. Nothing helps, and it is completely mysterious to me what is wrong!

The QA server is Windows 2003 running IIS 6, just like the Production server -- but the result is different.

I'm kind of out of ideas, so I am hoping someone here can suggest some.

1 Answer 1


Check the site bindings. If the bindings are invalid, the web site won't start and you will get 500 errors. In IIS Manager, you can see when a web site or application pool is stopped, but you may have to refresh the UI--when it first starts up, it may look fine, but when you refresh, you see that the site is stopped.

Another possibility is repeated crashes. If the application crashes during startup, it will try again, but after a few tries, IIS will give up and just stop the website. There may be something configuration-specific causing issues in production that don't happen in QA.

  • It turns out that the application pool for the site was stopped. Once I re-started it the site came back on line! Commented Dec 22, 2014 at 17:16

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