IIS 7 Service Unavailable 503 ERROR

Question

I am encountering a 503 - Service Unavailable error. I checked the event log and found this:

The Module name FastCgiModule path C:\WINDOWS\System32\inetsrv\iisfcgi.dll returned an error from registration. The data is the error.

Note: Every time I try to visit my website, I found that the DefaultAppPool will auto-stop. And also found this in event log:

Application pool 'DefaultAppPool' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

Answer 1

This is because your application pool is crashing more than 5 times in 5 minutes [default settings - Rapid Fail]

Instead of disabling Rapid Fail, you should consider taking Crash Dumps and try to find out the root cause. http://blogs.msdn.com/b/rahulso/archive/2006/03/02/what-is-a-crash-technically-in-asp-net-and-what-to-do-if-it-happens.aspx