Wednesday, 15 December 2010

ASP.NET (IIS) broken after installing updates

It looks like the recent Microsoft updates broke ASP.NET / IIS on my development machine.  Trying to launch any website hosted on my local IIS server returned a 500 error and the following error message: 

Calling LoadLibraryEx on ISAPI filter "C:\Windows\Microsoft.NET\Framework\v4.
0.30319\aspnet_filter.dll" failed 

And checking the event log just returned a similar error message: 

ISAPI Filter 'c:\Windows\Microsoft.NET\Framework\v4.0.30319\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 

After doing a bit of digging around on the web, the solution to this problem was to simply re-register IIS using the following command: 

c:\Windows\Microsoft.NET\Framework64\v4.0.30319>aspnet_regiis -r 

Everything then thankfully burst back into life!


tonyd said...

Be aware that running this script changes all app pools to run v4.0 framework which is maybe not what you want! I had to change mine back to v2.0
This did fix my problem though, so a big thanks.

Paul Hadfield said...

TonyD, Glad it helped and thanks for pointing the potential app pool issue. At the time I only had one website on the server that suffered the fault and I wanted it to be v4.0 so didn't see the issue - but I could imagine the problems it could cause.

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