IIS restart during Application Pool Recycles

Question

We have two applications - WebAPI and WCF service. Our WebAPI is consuming WCF service.

We have two different app pools for both applications with different recycle settings:

1. wcf application recycles every day at 1 am fixed with overlapping sessions.

2. webapi has default recycle settings.

We are getting wierd IIS restart daily at 1 am.

No event is logged in Event Viewer.

Note: We have grafana setup to monitor server and it sends alert daily at 1 am for server down.

What could be reasons for IIS restart?

Answer 1

have you seen application pool recycle in event log? as you know when recycling happened , all session in iis will destroy and a log wrote in Windows event log. so I need to send deliberate information about what you detect in your monitoring application. this is because of it might a false positive of your monitoring application. as you mentioned it didn't logged in event log, I suspected this problem Is for that. please send practical information to solve your problem.

Answer 2

It might be your application cannot refresh the app pools when you set their app pool refresh to happen at 1am.

I would look at the permissions given to the application pool. It could be the permissions aren't enough to restart it.

Other than that I would also recommend enabling Logging. You will find out your problem with Logging enabled.