The 'clr-namespace' URI refers to a namespace that is not included in the assembly

Question

I\'m trying to include in my XAML some classes which convert values. However, I\'m getting the following error when I compile:

Undefined CLR namespac

Answer 1

I had the same error. But apparently, it was just because of the path of the solution that I was trying to build. My path/directory/folder name contains some spaces.