# Don't debug an unmanaged application

Since most of the world is .NET these days, its my tendency to think I can find everything using SOS. Recently, I was attempting to debug a Windows service (Office SharePoint Server Search), and mentally thought “Well, its SharePoint, which is nothing more than a large .NET application, do its .NET as well.” After opening Windbg, and trying to load SOS, I got the following error:

“Failed to find runtime DLL (mscorwks.dll), 0x80004005
Extension commands need mscorwks.dll in order to have something to do.”

This perplexed me until I realized I was trying to debug an application that is not managed. To prove this, I ran the “lmvm mscorwks” command to see if mscorwks.dll was loaded. It wasn’t.