On our test box we're intermittently getting a blank page with "Service Unavailable" when trying to access one particular site that is built in Umbraco. Other sites are fine.
We seem to get a few errors in the event log like the one below before the AppPool stops working.
Faulting application w3wp.exe, version 6.0.3790.3959, stamp 45d6968e, faulting module kernel32.dll, version 5.2.3790.4480, stamp 49c51f0a, debug? 0, fault address 0x0000bef7.
Stopping and starting the AppPool fixes the error.
Any ideas on getting better error messages or what causes the "Service Unavailable" error?
The reason your getting the service unavailable message is because the application pool has crashed (which I'm sure your aware of) what you need to do is find what error is actually causing the pool to crash in the first place.
Firstly, I would check the event log, there may be an error in there that give you more details. But, more often than not, there won't be. If that's the case you need to look at using a tool like IIS Debug, that will monitor IIS and log information about crashes that you can use to debug this problem.