The specified framework 'Microsoft.NETCore.App', version '2.2.0' was not found

For whatever reason, .NET Core 2.2 is not installed by the ".NET Core cross-platform development" workload.

Open up the Visual Studio installer then go to the "Individual components" tab and you can install it from there:

In my case was missing x86 .NET Core 2.2.x Platform SDK (Visual Studio .NET 16.4 + .NET Core 3.1 SDK ; xUnit Test Project).

You can try this:

1. Exist directory 2.2.x in: C:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App ?
2. When no, try Download latest 2.2.x SDK for x86 platform from this URL: https://dotnet.microsoft.com/download/dotnet-core/2.2
3. Install and try ...
4. For more info about installed SDK and Runtime you can use command: dotnet --info