If you install an app that requires a specific version of the .NET Framework, the app’s setup program might install the .NET Framework on your computer or prompt you to install it. For example, the .NET Framework 3.5 is not automatically installed with Windows 8. To run apps that require the .NET Framework 3.5 on Windows 8, 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.
In general, you should not uninstall any versions of the .NET Framework from your computer, because an app you use may depend on a specific version and may break if that version is removed. Multiple versions of the .NET Framework can be loaded on a single computer at the same time. This means that you do not have to uninstall previous versions in order to install a later version.
Enabled the .NET Framework
You can also enable the .NET Framework 3.5 yourself through Control Panel. In Control Panel, choose Programs and Features, choose Turn Windows features on or off, and then select the .NET Framework 3.5 (includes .NET 2.0 and 3.0) check box. This option requires an Internet connection. You do not need to select the child items for Windows Communication Foundation (WCF) HTTP activation unless you are a developer who requires WCF script and handler mapping functionality.
If installing the .NET Framework 3.5 on demand or enabling it in Control Panel fails, you may get error messages.
Installing .NET Framework 3.5 via Windows Installation DVD:
If you cannot connect to the Internet, you can enable the .NET Framework 3.5 by using the Deployment Image Servicing and Management (DISM) command-line tool and specifying the installation media (ISO image or DVD) you installed Windows 8 from.
- In Windows 8, open a Command Prompt window with administrative credentials (that is, choose Run as administrator).
- To install the .NET Framework 3.5 from installation media located in the D:\sources\sxs directory, use the following command:DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:d:\sources\sxs
- /Online targets the operating system you’re running (instead of an offline Windows image).
- /Enable-Feature /FeatureName:NetFx3 specifies that you want to enable the .NET Framework 3.5.
- /All enables all parent features of the .NET Framework 3.5.
- /LimitAccess prevents DISM from contacting Windows Update.
- /Source specifies the location of the files needed to restore the feature (in this example, the D:\sources\sxs directory).