The solution is not ready to run out of the box

[ArvindRSingh]

On opening the Framework.sln no project was loaded and on trying to reload it says

BoxedMapper\Source\Boxed.Mapping\Boxed.Mapping.csproj : error : The project file cannot be opened by the project system, because it is missing some critical imports or the referenced SDK cannot be found.

Detailed Information:
Unable to locate the .NET Core SDK. Check that it is installed and that the version specified in global.json (if any) matches the installed version.

I have .NET core SDKs 1.0, 1.1, 2.0, 2.1, 2.2 and working for other projects.

[RehanSaeed]

You must have 2.2.300 of the SDK installed. See the global.json file.