There isn't very good documentation on this issue but usually it means you do not have the proper .NET Core SDK installed. In my case it was the latest for Visual Studio 2019.

Download it from here  https://dotnet.microsoft.com/download/dotnet/thank-you/sdk-3.1.411-windows-x64-installer

Also, often you may find that the CORE hosting bundlle is the issue, even though it may be installed. Simply run the installer and choose to "Repair"