Install the .NET Framework 3.5 on Windows 10, Windows 8.1, and Windows 8
You may need the .NET Framework 3.5 to run an app on Windows 10, Windows 8.1, and Windows 8. You can also use these instructions for earlier Windows versions.
Install the .NET Framework 3.5 on Demand
You may see the following configuration dialog if you try to run an app that requires the .NET Framework 3.5. Choose Install this feature to enable the .NET Framework 3.5. This option requires an Internet connection.
Enable the .NET Framework 3.5 in Control Panel
You can enable the .NET Framework 3.5 through the Windows Control Panel. This option requires an Internet connection.
Press the Windows key Windows on your keyboard, type "Windows Features", and press Enter. The Turn Windows features on or off dialog box appears.
Select the .NET Framework 3.5 (includes .NET 2.0 and 3.0) check box, select OK, and reboot your computer if prompted.
You don't need to select the child items for Windows Communication Foundation (WCF) HTTP Activation and Windows Communication Foundation (WCF) Non-HTTP Activation unless you're a developer or server administrator who requires this functionality.