1. try to download windows 8.1 upgrade assistance from here http://windows.microsoft.com/en-us/windows-8/upgrade-assistant-download-online-faq and check any incompatible driver and unistall it. i had mobile broadband driver incompatible
2.remove/unistall antivirus software or anti-spyware anti-malware program.
3.update to latest graphics driver version from your graphics card menufacture site.
4.clear cache of windows app centre by
Open the RUN dialogue box. You can do so by pressing Windows + R keys.
Type WSReset.exe, and press enter.
After this the store will open and automatically it will clear the cache and will present you the message: “The cache for the store was cleared. You can now browse the store for apps”
5.now open the windows store and donwload windows 8.1 again and this time no blue screen or no error willl appear and your update to windows 8.1 complete in half an hour.
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