Hi there, I just wanted to share how I solved the problem in my case.
I had previously tried to no avail nearly every single solution proposed on this and many other threads, so I guess that my experience could be helpful for those having a similar problem.
What I did:
- In-place upgrade to Windows 8.1 Pro. Meaning:
- I downloaded the ISO file (in my case I had a Technet subscription still available, but I'm sure they can be found elsewhere); need to be same language and bits as the already installed version.
- Mounted the DVD image using Windows Explorer.
- Launched the Setup from within Windows, and select to install while keeping everything (files, settings, profiles, etc.)
- Because the setup program did not accept my good old W8 license key, I used the generic keys available in this website for the installation (then activated with my original W8 key after the first boot).
- After booting back to my desktop I just run Windows Update several times until I reached the key KB2919355 "Update"; only this time it worked without problems.
So here I am finally on a fully updated Windows 8.1 Update, while having kept all my files and programs intact. And btw, it was faster to reinstall Windows than to run the sfc tool alone...
Hope this may help someone.
PS: I tried going straight to the ISO with Windows 8.1 Update (which is also available in TechNet), but unfortunately that didn't work out, and the installer stopped at 33%. So if you are using W8.1 you really need to get an ISO for that specific system.