I\'m, a WPF & Xaml-noob, for console applications it has worked for me to simply give the relative path to the executable to access a file. It doesn\'t seem to work in x
URIs can be confusing, as they can refer to both files on disk and resources in the application. So a relative path could be to a resource in the app, when you intend it to be on disk.
You can use the siteoforigin authority to force relative file URIs. This blog explains this more, but here an example:
pack://siteoforigin:,,,/path4.ico