Using XAML Islands on Windows 10 19H1: fixing the "Catastrophic failure" exception

Thanks a lot Mateo, it really helps. But I still have few interrogations/problems that you seems to be the key to the solution.

I followed Thomas Claudius Huber post: https://www.thomasclaudiushuber.com/2019/04/23/net-core-3-use-uwp-controls-in-wpf-with-xaml-islands/ and video (PluralSight) of Olia Gavrysh - Building Modern .Net Desktop Apps with .NET Core and Windows 10: DEVintersection 2019.

Note: Olia says at minute 40:40 : Minimum version of Windows talking about "maxversiontested". Is this a minimum or maximum version (one is the opposite of the other)? Does Microsoft will fix that?

I used <maxversiontested Id ="10.0.18362.0"/> but the XamlDesigner message says in the error message "0.0.18226.0". It's really comfusing, it would be nice the remove the ambiguity.

After everything was added like described by Thomas and Olia (and you), I still got the error from XAML designer:

"Catastrophic failure\r\n\r\nWindowsXamlManager and DesktopWindowXamlSource are supported for apps targeting Windows version 10.0.18226.0 and later. Please check either the application manifest..."

OK, although the designer say that, it compiled fine and worked fine, at least in appearance. Just in appearance, because I'm also not able to access "MyMapControl" from code behind although I set x:Name = "MyMapControl".

Also, as a side note, the designer does not really help if it says errors that do not exists. I Know it's like that for at least 10 years (Xaml Designer, in some circumstance, show some false errors although everything compile fine) but this one, a new one, really does not help when we are trying new stuff. Can we expect Microsoft to fix the Xaml Designer in order to show real errors? I can sent you samples of many types of false errors.

Also, I can't access the MapControl from code behind. Do you have any idea why?