install .Net Core 2.2.301 and upgrade your app on the earlier version

Get it here. It will give you: .NET Core Runtime 2.2.6 (right-click on your projects in Visual Studio 2019, pick "Properties" and then at the "Application" tab flip the "Target framework:" setting to ".NET Core 2.2") You may see an error like so in your UI project:

Detected package downgrade: Microsoft.AspNetCore.Razor.Design from 2.2.0 to 2.1.2. Reference the package directly from the project to select a different version.

 
 

To fix this, you could try to open the .csproj file in Notepad and splice this just inside the closing PropertyGroup tag:

<TargetLatestRuntimePatch>true</TargetLatestRuntimePatch>

 
 

But, honestly, that didn't work for me. I instead ran these NuGet commands back to back:

1. uninstall-package Microsoft.AspNetCore.Razor.Design
2. install-package Microsoft.AspNetCore.Razor.Design