Recently users where getting this error message:
“Revocation information for the security certificate for this site is not available. Do you wish to proceed?”
when they accessed a website.
After investigation it turned out that the certificate revocation list distribution point, which is found (in IE anyway), under:
Page properties, certificates button, look on the details tab for CRL distribution point.
Was no longer accessible, due to some interesting firewalls that had been put in place. On opening access to this appropriately, the message no longer appeared, as the revocation information was then available.
Recently on migrating to a new platform, we experienced this error:
Error Code 64: Host not available
This was quite mysterious as it only occured after a IIS reset, and pressing F5 fixed it.
The only error which occured was an exception displayed in the system event log.
A process serving application pool ‘<Pool Name>” suffered a fatal communication error with the Windows Process Activation Service. The process id was ‘2100’. The data field contains the error number.
No other debug information was available anywhere.
Unfortunately this was a production server I was building, so I didn’t want to install any debug tools.
Anyway, eventually I discovered this was being caused by an unhandled exception in our own code, which was not being caught.
In summary, this had nothing to do with IIS settings, ISA Server settings or Sharepoint, but was purely our own code.