Our hands were tied recently when we had to develop a 32 bit web app due to the reliance on a 3rd party app that was 32 bit only.
We quickly worked out how to get the app running in 32 bit mode in IIS7 just by setting the “Enable 32-Bit Applications” setting within the application pool used for the app.
This worked great until we went to do this on a server running OWA 2010. After setting the application pool to run 32 bit apps, we still got an error:
HTTP Error 503. The service is unavailable.
And as an added bonus, the application pool was now stopped. Yippee – I guess that was 5 errors in less than 5 minutes!
A quick look in the Application event log showed the following error:
The Module DLL ‘C:\Program Files\Microsoft\Exchange Server\V14\Bin\kerbauth.dll’ could not be loaded due to a configuration problem. The current configuration only supports loading images built for a x86 processor architecture. The data field contains the error number. To learn more about this issue, including how to troubleshooting this kind of processor architecture mismatch error, see http://go.microsoft.com/fwlink/?LinkId=29349.
The Source was IIS-W3SVC-WP and the Event ID was 2282.
A bit of research pointed us in the direction of setting the kerbauth.dll to be 64 bit only in the applicationHost.config file for IIS (located in C:\Windows\System32\inetsrv\config). So we stopped IIS and edited the file. In the globalModules section, we found the line for kerbauth, and added the precondition=”bitness64” attribute as follows:
<add name=“kerbauth” image=“C:\Program Files\Microsoft\Exchange Server\V14\Bin\kerbauth.dll” preCondition=“bitness64“ />
We restarted IIS (and also the app pool!) and now the app showed the following error:
HTTP Error 500.0 – Internal Server Error
Calling LoadLibraryEx on ISAPI filter “C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\owa\auth\owaauth.dll” failed
So we applied the same theory again, and again for each dll that caused an issue – luckily for us there were only two – owaauth.dll and AirFilter.dll. Both were listed in the <isapiFilters> section of the applicationHost.config file:
<filter name=“Exchange OWA Cookie Authentication ISAPI Filter” path=“C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\owa\auth\owaauth.dll” enabled=“true“ preCondition=“bitness64“ />
<filter name=“Exchange ActiveSync ISAPI Filter” path=“C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\sync\bin\AirFilter.dll” enabled=“true“ preCondition=“bitness64” />
We restarted IIS again and voila – a happy application, and OWA still worked to boot. Who says you need to run 32 bit apps on a separate server! Happy days…
Now I’ve just gotta get that song out of my head… “taking care of bitness and working overtime…” ;-)