Application pool stops randomly within in a specified time period. What can be possible reason?
One of possible reason may be Rapid Fail Protection in IIS. Rapid-Fail Protection disables application pool if it crashes several times within in a specified time period. It prevents the failing application pool from getting into a continuous loop of crashing. This is useful when an application goes out of control which could overload the server.
To prevent an Application Pool from stopping, you can disable Rapid Fail Protection in IIS, please refer to this article for more information:
General instruction to disable Rapid Fail Protection for application pool is the following:
Open Internet Information Services (IIS) Manager->Application pools->choose application pool->Advanced Settings
Scroll down to Rapid Fail Protection and change the option Enabled from true to False. Click OK to apply the changes.