We had a weird case some time ago on one of our Windows 2003 server. After we made changes to IIS configuration, more specifically – one virtual folder – the whole IIS stopped. This of course caused outage for some applications, some were switched over to secondary server by load balancer.
User making the change said he didn’t do a thing to whole IIS, only made changes in one virtual folder and recycled its application pool. Moreover, he checked other applications’ accessibility after making this change. All was fine.
What we cound find in the logs was:
Event Type: Information
Event Source: ASP.NET 2.0.50727.0
Event Category: None
Event ID: 1023
Computer: Web server name
That directed us to the following Microsoft KB article: If you make some changes to the ASP.NET 2.0 Web site properties and you click the ASP.NET tab in IIS Manager, the W3SVC service may be restarted unexpectedly. It turns out that if you make changes to a virtual folder, and click the ASP.NET tab, IIS can restart itself. What’s more, it does it not immediately, but after some short amount of time.
And in our case, IIS did not restart. It stopped and then couldn’t start for some reason. Simple
iisreset /start did the job, but the idea of webserver stopping itself when it wants is hillarious.