I’d recently put Windows 8 on a test machine at work and started installing what software I needed. Pretty quickly I found I needed to install .Net Framework 3.5 which is now a ‘Feature’ instead of a separate download. Switching this on prompted me to download files from Windows Update. That seemed to go OK for a while. Unfortunately, after a few minutes, it failed. Error code 0x800F0906 leads you to troubleshooting articles such as: .NET Framework 3.5 installation error: 0x800F0906, 0x800F081F, ......