If you are trying to enable .Net Framework 3.5 on Windows 8 Customer Preview, you may encored the following error – NOTE this doesn’t occur on all machine

Windows could not download necessary files from Windows Update. Check your network connection.

Error code: 0x800f0906

 

To solve the issue:

  • Mount the ISO file used to install Windows 8 – NOTE: Microsoft has finally included a feature to mount ISO file without any tools, you just have to double click on the ISO file to get it mounted on virtual DVD drive
  • Locate the source files for the .Net Framework (x:\sources\sxs\) and copy all the content to your local drive (let’s say c:\net)
  • Open a command prompt with elevated privileges (run as administrator) and run the command Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:c:\net /LimitAccess

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Et voilà