Windows 8.1 could not be installed (0x101 - 0x20017)
I installed Windows 8.1 (Enterprise) as an update on my corporate notebook and was greeted with this error after the first reboot in the install process:
Then it reboots again and you are back to your Windows 8 without the dot one!
I have a full encrypted system partition using TrueCrypt and this was the problem in my case. I took a wild guess on this and decrypted the drive. Then I updated to Windows 8.1 and this time it worked flawlessly. After the update I encrypted the drive again.
Issue solved :-)