Jan 062012

You have a managed application crash dump and you would like to load sos.dll, to use the powerful commands it provides to help with managed debugging, but the load of sos.dll always fails.

The command that you are executing for loading sos.dll is…

0:015> .loadby sos clr 

Unable to find module ‘clr’

On enter you see the above error and you are not sure what is going on. So in order to understand the error message it is important to understand what .loadby command does. “.loadby sos clr” means load sos.dll from where clr.dll is loaded.

So as you might have guessed by now if clr.dll is not loaded then sos.dll cannot be found. This is what the error means when it says “Unable to find module ‘clr’”. All it means is clr.dll is not in the loaded module list which means there is no path to locate clr.dll.

So how can I fix this error? In order to fix this error you must understand that clr.dll has been introduced into .net applications from .net 4.0 and prior to that we used to have mscorwks.dll.

So if your .net application is not a 4.0 app then clr.dll won’t be loaded, yes you will have to use mscorwks.dll instead…

0:015> .loadby sos mscorwks 

But you are damn sure that the application that crashed is a .net 4.0 application but you still see the error! All I can say is clr.dll is not loaded. Wait for it to load or break on its load and then execute

.loadby sos clr.

So how to break on a module load…

0:015> sxe ld clr 

This will for sure help!

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