How do I determine the dependencies of a .NET application?

I find the small utility AsmSpy an invaluable tool to for resolving issues with loading assemblies. It lists all assembly references of managed assemblies including assembly versions.

Run it in a command prompt in the directory of the .dll with the following arguments:

asmspy . all

Install it quickly with Chocolatey:

choco install asmspy

Open the assembly file in ILDASM and look @ the .assembly extern in the MANIFEST

Dependency walker works on normal win32 binaries. All .NET dll's and exe's have a small stub header part which makes them look like normal binaries, but all it basically says is "load the CLR" - so that's all that dependency walker will tell you.

To see which things your .NET app actually relies on, you can use the tremendously excellent .NET reflector from Red Gate. (EDIT: Note that .NET Reflector is now a paid product. ILSpy is free and open source and very similar.)

Load your DLL into it, right click, and chose 'Analyze' - you'll then see a "Depends On" item which will show you all the other dll's (and methods inside those dll's) that it needs.

It can sometimes get trickier though, in that your app depends on X dll, and X dll is present, but for whatever reason can't be loaded or located at runtime.

To troubleshoot those kinds of issues, Microsoft have an Assembly Binding Log Viewer which can show you what's going on at runtime