Fix: The tag XXX does not exist in XML namespace ‘clr-namespace:YYY’
I just had some big trouble troubleshooting the Visual Studio / XAML compiler error message: The tag XXX does not exist in XML namespace ‘clr-namespace:YYY’ It turned out this occurred because I had a Silverlight library with Assembly name X and default namespace X (at properties pane), but was using it from a demo project [...]
