application pool being auto-stopped when enabled for 32 Bit applications


does anyone know why the ApplicationPool in IIS 7 is being stopped ONCE I enable it for 32 bit support ?

I see the following Error in the Event viewer:

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.

I hope someone can help....

I am using Windows 2008 Enterprise R2 with Exchange 2010 installed on it....

Thank You
Best regards
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if you want to run ASP.NET 1.1 and ASP.NET 2.0 at the same time, you must run IIS in 32-bit mode.

Please refer microsoft article

FalconQAuthor Commented:
hello David,

thank You for reply !!

I found the solution for this problem. I am using only .Net 2.0 at the time so that was not a problem.
Not sure why this happens but in my case I got the error described below:

The Module DLL 'C:\Program Files\Microsoft\Exchange Server\V14\Bin\kerbauth.dll' could not be loaded due to a configuration problem

and I found some articles where the people have another errors like for example one below:

The Module DLL C:\Windows\system32\RpcProxy\RpcProxy.dll failed to load could not be loaded due to a configuration problem

and it could be another dll`s too... depending on our installations

BUT both of these problems caused the error when trying to run an 32 bit enabled web app in our browsers:

HTTP Error 503. The service is unavailable

So the solution for this problem is:

 in the file "applicationHost.config" located at:


add this line:  preCondition="bitness64"

Example in my case:

 <add name="kerbauth" image="C:\Program Files\Microsoft\Exchange Server\V14\Bin\kerbauth.dll" />

And this is after the change, when we add the line as described above:

 <add name="kerbauth" image="C:\Program Files\Microsoft\Exchange Server\V14\Bin\kerbauth.dll" preCondition="bitness64" />

than just start the AppPool again and 32 bit application will now work just fine.. and our AppPool wil not be stopped again....

So the point is only to add the line: preCondition="bitness64" behind the .dll file WHICH displays the error.

Best regards

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FalconQAuthor Commented:
issue fixed
Thanks from Switzerland
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