As mentioned, primitive data types are defined under .NET Framework itself and it's not language specific. It means you can use these data types across all languages supported under .NET Framework. It doesn't mean you can use these primitives under different flavors of .NET Framework. For example, if a data type is defined under .NET Framework version 4.6.1, and it's not defined under .NET Core 2.0, your code will fail under .NET Core 2.0.
Also, make sure you have the latest version of Visual Studio, which is 2017 at the time of writing.
