If the user performs a clean installation of Windows 8, and then installs apps that require .NET Framework 3.5 (or 2.0), they will trigger a request for the necessary .NET 3.5 files. Normally the missing files will be downloaded from Windows Update (after asking the user for permission), but if access to Windows Update is not possible, enabling .NET Framework 3.5 will fail unless an alternate source for the missing files has been specified
For machines that are configured to use WSUS for servicing, you can set a registry entry to allow the machine to use Windows Update for enabling .NET 3.5 instead of WSUS (servicing will still be done from WSUS if you do this).
You can set via Group Policy “(Local Computer Policy -> Computer Configuration -> Administrative Templates -> System. Select the setting “Specify settings for optional component installation and component repair”. Enable this one .
Check mark the second option
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