The tag 'XXX' does not exist in XML namespace 'clr-namespace:YYY'

Question

I have implemented a converter to convert Int32 to String to be able to binding a property to a textBox.

I implement this converter in the namespace MyApp.Converters and

Answer 1

In my case, the assembly which contained the namespace was not physically there.

I checked the references of the assembly that had the build error and looked at the properties of the referenced assembly in question.

I navigated to the path and discovered the assembly was indeed missing (which I realised was my own doing), giving rise to the misleading error.