.NET Framework 4.5 on Win 8 is included with Windows 8 and installed on your computer with the operating system. but. NET Framework 3.5 is not automatically installed with Windows 8. To run an application that requires .NET Framework 3.5 on Windows 8, you must have version 3.5. enabled on your computer. There are two ways you can do this: by installing or running the .NET Framework 3.5 applications (that is, by installing .NET Framework 3.5 when needed), or by enabling the .NET Framework 3.5 in Control Panel. Two options require an Internet connection.
Important note:
Use .NET Framework 3.5 for applications built for versions 2.0, 3.0, and 3.5.
Installing a Windows language pack on Windows 8 that does not have .NET Framework 3.5 installed will cause the .NET Framework 3.5 installation to fail. Install .NET Framework 3.5 before installing any Windows language packs.
Windows CardSpace is no longer available with .NET Framework 3.5 on Windows 8.
Manual installation of .NET Framework required if the application requires it. NET Framework 3.5, but does not find an enabled version on your computer, it will display the following message box at installation time or when you first run the application. In the message box, select "Install this feature" to enable .NET Framework 3.5. This option requires an Internet connection.
Prompt to install .NET Framework 3.5 on demand
Enable .NET Framework in Control Panel 3.5
You can also enable .NET Framework 3.5 through the "Control Panel" in "Control Panel In ", select "Programs and Features", then select "turn on or turn off Windows features", and then select the Microsoft .NET Framework 3.5.1 checkbox. This option requires an Internet connection.
Enable or disable Windows features in "Control Panel"
If you install .NET Framework 3.5 as needed or if it fails to enable it in "Control Panel", you can receive the following error message One of
0x800f0906:"Windows cannot connect to the Internet to download the necessary files. Make sure you are connected to the Internet and click "retry" to try again.
0x800F081F:"Unable to complete this change. Please restart your computer and try again.
These messages may be displayed for the following reasons:
Your computer is not connected to the Internet. Please connect and retry the operation.
If your computer cannot connect to the Internet, you can enable it by using the installation media (ISO image or DVD) from which Windows 8 is installed. NET Framework 3.5. Load the Windows 8 installation media and type the following command from an elevated command prompt:
Dism /online /enable-feature /featurename:NetFx3 /All /Source:x:sourcessxs /LimitAccess
where x : Is the drive letter of the Windows 8 ISO image or DVD.
The ISO installation method can refer to: http://win8e.com/jiqiao/7131.html
The local source is being used, but the network location is inaccessible or does not have the appropriate content. Enable .NET Framework 3.5 from the installation media in the contents of the bullets described earlier.
Your administrator has configured your computer to use Windows Server Update Services (WSUS) to perform services instead of using Windows Update. Your administrator enables policies that use Windows Update instead of WSUS.