Undefined CLR namespace - No solution found

Question

I've been researching for a while now trying to find a reason why the following would be occuring, but no solutions on StackOverflow or Google are able to help me.

I have a custom UserControl that is attempting to reference a namespace within the same project:

xmlns:my="clr-namespace:ColorPicker"

however when I compile I get the following error:

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

This is resulting in not being able to build my project or reference other custom controls within the xaml, generating these kinds of errors:

The type 'my:ColorSelector' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built.

I've attempted all the solutions given in these posts:

adding a custom namespace to xaml

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

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

Undefined CLR namespace

Also, just to be clear, I'm not getting any other errors about other files in this project, so it doesn't seem like it could be the result of other files not compiling.

UPDATE: A sample project that produces the error for me can be downloaded here: http://www.filefactory.com/file/28fbmhj3f4qj/n/ColorPicker_zip

Answer 1

Your first linked question has the answer. The answer is: you have to build the assembly containing the namespace and referenced classes/controls before you can reference it in .xaml. I commented out your xaml namespace declarations, then commented out the xaml elements from those namespaces, then commented out the C# code that broke as a result of those elements no longer being declared. In other words, I kept commenting till I could build successfully. Once the assembly built, I uncommented the xaml namespace declarations, then the elements. This gave an error about needing to use x:Name instead of Name on those elements, so I did so. Then uncommented the C# code and it builds.

Answer 2

xmlns:my="clr-namespace:ColorPicker;assembly=ColorPicker".

This worked for me! It's faster and less annoying!