Had this problem recently withoiut a clients computer. First of all it would download and attempt to install the 8.0 to 8.1 upgrade but then it kept repeatedly getting stuck at certain percentages such as 82% for hours at a time. When I finally had to hard reset it Windows said the update could not be installed and rolled back to 8.0.
I then had to reinstall all the windows updates again before I even had the option of 8.0 to 8.1. When it was available to my dismay I got the following error message when i tried to download it.
Luckily the fix was really easy. Here is what to do…
run an elevated command prompt – press the ‘WINDOWS’ key and ‘X’ and then press ‘A’
in the command prompt that appears simply type ‘net stop wuauserv’ and press ‘enter’
and then ‘net stop bits’ and press ‘enter’
These commands stop the windows update service from running which appears to be the cause of the problem. Windows thinks its already updating itself so will not let you download and install another update.
I have seen posts recommending deleting all the updates in C:\Windows\SoftwareDistribution but I did NOT have to do this myself.
Reboot and try again. Keep in mind the whole process does take more than an hour so just let your computer do its thing.
Enjoy Windows 8.1 🙂