I have installed the community Visual Studio 2019 version 16.4. and clone the solution of .NET Core 3.0 but no project loaded something wrong in the SDK. I have installed the SDK and runtime for 3.0 and 3.1, but still can not load any project.
You could fix the VS 2019 issue with the below steps
dotnet --list-sdks
to know the exact version of the SDK installed References: