March 10, 2010

MS Exchange 2007 ISAPI error

By Geekphreek

We all love a bit of complaining about Microsoft and then they went out and made sure we’d bitch, by allowing 32bit and 64bit .NET apps with a plugin to IIS, and then not allow them to run concurrently.

The trap I’ve fallen in to is that I am suffering with the amazing Service Unavailable screen on my OWA. The event log is screaming at me with W3SVC-WP errors:

ISAPI Filter ‘C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\\aspnet_filter.dll’ could not be loaded due to a configuration problem. The current configuration only supports loading images built for a AMD64 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

For more information, see Help and Support Center at


Okay, so we know this sucks. Finding the info to fix can be a little tricky so here, fire up a cmd shell and run these 2 lines:

cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 0

%SYSTEMROOT%\Microsoft.NET\Framework64\v2.0.50727\aspnet_regiis.exe -i

The first line allows 64bit only, the second reinstalls asp .NET.

Go take a look at your OWA or Exchange web services and they should be back to normal.