I have same problem. Fresh windows installation.
I tried to download 64bit version of .NET 3.5 cab (cca 70MB) but no luck installing via dism. I also tried to do:
Dism /Online /Cleanup-Image /StartComponentCleanup
restarting and trying to install via dism and Windows components but both fail on error:
Dism /Online /Cleanup-Image /RestoreHealth
I searched trough internet many times and only one person said he actually fixed this by downloading .cab package containing ONLY 64bit .NET, that 70MB is said to be both 32/64bit version. But when I tried to find it I had no luck. I don't want to do a new installation because I'm developer and designer dependent on many software and utils, which require at least two-day post installation process to have everything I need for my work.
An error occurred – Microsoft-Windows-NetFx3-OnDemand-Package Error: 0x800736b3
The referenced assembly is not installed on your system.