"The debugger was unable to find the registration for the target application."

I have a UWP app (from a Xamarin.Forms app) which debugs fine on the computer. But when I try to debug on a phone, I get the following error:

Unable to debug Windows Store app '....exe'. The debugger was unable to find the registration for the target application. If the problem persists, try uninstalling and then reinstalling this application.

The app does get installed on the phone and can be executed there. But I can't debug it with Visual Studio.

Meanwhile, the error I see in the error list in VS is:

DEP6700: LaunchMsvsmon failed on the device side. [0x800401F3] Invalid class string (Exception from HRESULT: 0x800401F3 (CO_E_CLASSSTRING))

I uninstalled both on the computer and on the phone, I rebooted both, I deleted the .vs folder, bin and obj folders... Nothing helped.

What are these errors telling me?

Currently, the Maximum SDK version supported by windows phone is Windows 10 Creators Update (Build 15063). If your project target version is Fall Creators Update (Build 16299), it will not be supported.

If your Shared project is Portable Class Library, you could modify the target version to Windows 10 Creators Update (Build 15063).

However, if you have used .NET Standard shared project, and it only support Fall Creators Update (Build 16299). You could not modify the target version.