I got asked to modify a feature in an application written by myself that I lost the source code. So I used Telerik JustDecompiler. It worked far better than everything else I've tested by I'm having an issue with the mainwindow.xaml file. It doesn't open in the GUI designer at all. When I try to open it within the visual studio Project, it ask me to select the encoding and the file fail to show, with the error:
https://i.stack.imgur.com/kq9Gl.png
How do I fix this?