Question

Trying to find a way to prove that my program is not running correctly because the version numbers of the dll’s my interops are pointing to are different i.e. different GUIDs.

Works on my machine, not on “theirs” with the different dll’s.

Can anyone recommend some debugging tools that let me watch the program as it starts up and see things like “looking for dll, not found, quitting”?

Is there logging tool available that would report these things to me?
If so I’m not aware of/using it.

Answer 1

You get an exception when a DLL isn’t found. Or more commonly in your case, a COMException as soon as you try to use the interop library in your code. One drastic mistake you could make is catching such an exception. That’s a very common mistake. But don’t, undiagnosable failure is the result. There is rarely any point in letting your program continue running when an important chunk of code is just missing. Logging it isn’t hard when you use AppDomain.UnhandledException.

This should at the very least provide you with decent diagnostics that help you to fix your code. You cannot get this started until you get good exception info. Pre-emptively fixing rather than waiting for the customer to get back to you with an exception trace usually requires you to recreate possible client configurations and testing your code. Highly advisable btw with 4 versions of IE in common use. You’ll need a virtual machine so you can install the different OS and IE versions and test your code. Making the OS and IE version a system requirement is not unreasonable, ymmv.