If you’ve experienced this error message: “The following feature couldn’t be installed: .NET Framework 3.5 (includes .NET 2.0 and 3.0)
Then this is your solution (at the moment):
dism.exe /online /enable-feature /featurename:NetFX3 /Source:g:\sources\sxs
from an administrative CMD. “g” is the drive where you have your win8 installation files.