HTTP Error 503. The service is unavailable

Question

I'm struggling to setup the environment in IIS8, I searched a lot but couldn't find a right solution.

I checked the error logs, but no idea.

C:\Windows\System32\LogFiles\HTTPERR

1. 2013-10-09 09:28:39 192.168.43.205 60172 192.168.43.205 80 HTTP/1.1 GET / 503 2 AppOffline qa.hti.local
2. 2013-10-09 09:28:39 192.168.43.205 60192 192.168.43.205 80 HTTP/1.1 GET /favicon.ico 503 2 AppOffline qa.hti.local

Then in Event Viewer:

WARNINGS:

1. A listener channel for protocol 'http' in worker process '11188' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.
2. A listener channel for protocol 'http' in worker process '7492' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.
3. A listener channel for protocol 'http' in worker process '9088' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.
4. A listener channel for protocol 'http' in worker process '9964' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.
5. A listener channel for protocol 'http' in worker process '7716' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.

I don't understand what the warning means.

ERROR: Application pool 'qa.hti.local' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

Note: I learned that consecutive 5 failures leads to APP Pool crash, and this can increased. I also tried increasing this but no success.

Please share your thoughts.

Answer 1

I came across this question as I was experiencing a similar issue and searching for a solution.

My problem specifically had to do with our IIS shared configuration. We had enabled a feature in IIS on one of the servers (Http Redirect) that was not installed on any of the others so the server 'features' were out of sync with all the servers.

I was able to resolve the issue by uninstalling the new addition on the first server so it was back to matching the others. An IIS reset later and the AppPools were no longer going down and all was back to normal.

So if you are using IIS Shared Configuration and the IIS is creating 'Service Unavailable' errors and the AppPools are going down, this can be a symptom of the system configuration being out of synch which is corrupting the shared configuration. Hopefully this post will help someone find the solution faster than I was able to.