01-01-2016 12:08 PM
After almost 2 (!!!) years I was finally able to update from Windows 8 to Windows 8.1 with my Lenovo B5400
I tried almost everything that is suggested in the official Windows answers/support threads e.g. http://answers.microsoft.com/en-us/windows/forum/windows8_1-windows_install/windows-81-installation-...
There Windows suggest clean installs, refreshing, language specification among other things.
Nothing worked. Anyway some things I found helpful (of course this does not mean, that this will help you, if you have the same problem, but you might want to try - especially when your warranty is over, and you can't send the machine in): Uninstall McAffee AV (which is pre-installed by Lenovo) and then run the McAffee uninstaller (from their website). Also I removed the Adobe Bridge software. After studying the setupact file (where windows logs the installation procedure), I decided to turn on the Windows customer experience improvement program.
Finally (and I suppose most importantly) I followed the instructions here (please be careful this is for advanced users and can cause serious problems with your machine) : https://neosmart.net/wiki/fix-uefi-boot/#Fix_1_Use_diskpart
(watch out there seems to be an error in step 28: when it says "/s x:" I think the x: should be replaced with the letter of the system partition. Double-check here: https://technet.microsoft.com/en-us/library/hh824874.aspx)
Well, this did the trick for me and I could finally update to Windows 8.1