.NET Framework 3.5 on Windows 8

For example, the .NET Framework 3.5 is not automatically installed with Windows 8 or Windows 8.1. To run apps that require the .NET Framework 3.5 on Windows 8 or later, you must enable version 3.5 on your computer. There are two ways you can do this: by installing or running an app that requires the .NET Framework 3.5 (that is, by installing the .NET Framework 3.5 on demand), or by enabling the .NET Framework 3.5 in Control Panel. Both options require an Internet connection.


https://msdn.microsoft.com/en-us/library/hh506443(v=vs.110).aspx