Is it possible to debug the DLL of a built in _layouts application page?

Question

I'm getting a vague error (as below) on the built-in _layouts/ChangeFieldOrder.aspx page which uses the DLL "Microsoft.SharePoint.ApplicationPages".

"Object reference not set to an instance of an object"

Is there any way to attach to that DLL so I can step through it and see exactly what's causing the error?

Answer 1

You'd have to use something like .NET Reflector and its Visual Studio plugin in order to actually step through the code in the debugger.

With something like ILSpy you can take a look at the code, but not step through it, which may well be enough to discover what's going wrong without spending money.

Answer 2

I would check the ULS logs with a tool like the ULS Viewer.

Start a trace, load the page again and check the viewer. It may reveal more details about what's happening to cause the problem.

Here's a link: http://archive.msdn.microsoft.com/ULSViewer