Why does the application pool automatically stop?-Collection of common programming errors

I’m doing performance testing for my MVC internet application using IIS 7.0

Sometimes the application pool stops and I get an error saying “service unavailable” in my browser. I then have to restart the pool.

Why is the pool automatically stopped, and how can I solve this problem?

update And my log file has : “C:\Windows\Microsoft.NET\Framework64\v4.0.30319\webengine4.dll returned an error from registration. The data is the error.”

  1. The application pool stops when it can’t recover from an error/crash. Look at the Event Viewer under Windows Logs > Application to see the exception(s) that caused the crash. The Source column will mention something like ASP.NET 4.0.30319.0