My ramblings on the stuff that holds it all together
OWA 503 Service Unavailable following 973917 update
I’ve seen a couple of instances of this in the last week where previously working Exchange 2003 servers suddenly stop serving Outlook Web Access (OWA) Requests overnight
Investigating the eventlog shows the following entry which corresponds with stopped application pools in IIS Manager;
Event Type: Error
Event Source: W3SVC
Event Category: None
Event ID: 1059
A failure was encountered while launching the process serving application pool ‘DefaultAppPool’. The application pool has been disabled.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
This seems to be related to a recent Microsoft Update – 973917 uninstalling the hotfix, followed by a reboot immediately resolves the problem and OWA starts working again.
I’ve also had reports from people that this update has affected some other bespoke IIS applications, again uninstalling the patch seems to resolve the problem.
This situation seems to arise from a mismatch of installed binaries – now I thought system file protection and the .msi based patch installers were supposed to avoid this situation from Windows 2003 and onwards – anyway for more information on the cause and how to resolve without uninstalling the 973917 patch see the following links