Why doesn't XAML see the class?

Question

C++ / C#

I open the MVVM Light Toolkit base project and see the following error.

This happens if you specify any of your own classes, converters, and so on. Moreover, the studio perfectly auto-completes the names of these classes, but the compiler swears.
Not a critical error, the project is going and working, but I would like to understand what's the matter?

Answer 1

Oh, I struggled with this for a long time. It helps restarting the aircraft, transferring files to a new project, something else. Fuck it you will understand why it behaves like that

Answer 2

Solution for your problem:

<Application.Resources>
        <ResourceDictionary>
           <vm:ViewModelLocator x:Key="Locator" d:IsDataSource="True"
                                 xmlns:vm="clr-namespace:e3Shell.CableConnectionTable.ViewModel" />
        </ResourceDictionary>
    </Application.Resources>