The example projects are built against ASP.NET Core 2.0.
They should build cleanly with no errors or warnings.
Once ASP.NET Core 2.1 is installed, these projects will build with some warnings stating certain Microsoft tools are now part of the .NET Core SDK.
To remove these warnings, edit the project files to remove each <DotNetCliToolReference>.
The projects may also be moved up to ASP.NET Core 2.1 but this isn't necessary.
For more information, please refer to:https://docs.microsoft.com/en-us/dotnet/core/migration/20-21https://docs.microsoft.com/en-us/aspnet/core/migration/20_21