Last week I deployed a sample application to my test IIS environment. But when I tried to browse to the site I got a 503 Service Unavailable Error. When I looked inside IIS, I noticed that the application pool had a problem starting up.
The event log brings more inside into the issue:
The Module DLL 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\isapi\spnativerequestmodule.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.
‘Web Server Extensions’? This rings a bell, I have a Sharepoint 2013 installation on the same server. But why does IIS tries to load a Sharepoint DLL inside my own site? The website I deployed has to run as a 32bit process, something that Sharepoint 2013 doesn’t seems to like. The finger points to a new ISAPI module in SharePoint 2013 and its stopping our 32bit site from loading.
It looks like there is a bug in Sharepoint where a global module isn’t conditionally loading the right DLL depending if it’s a 32 or 64bit application. Let’s have a look at the globalmodules by executing the following command:
appcmd.exe list config /section:globalmodules
And indeed we find a reference to the DLL mentioned inside the event log without any kind of precondition:
<add name="SPNativeRequestModule" image="C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\isapi\spnativerequestmodule.dll" />
Let’s fix this by applying the following command
appcmd.exe set config -section:system.webServer/globalModules /[name='SPNativeRequestModule'].preCondition:integratedMode,bitness64
This changes the configuration to the following:
<add name="SPNativeRequestModule" image="C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\isapi\spnativerequestmodule.dll" preCondition="integratedMode,bitness64" />
And now our 32bit application loads without any issues…