My install downloaded all of the files from the internet just fine, then it rebooted and started the actual upgrade. Got to 91% and the installation just hung for 10 hours.
I phoned microsoft, they told me to power down the PC and reboot.
PC Message on reboot - REVERTING TO PREVIOUS VERSION OF WINDOWS ----
What now?
I have also had problems with this latest Win 10 update.
I have been stuck on this message below for over 24 hours now. See attached screen capture below.
As for the latest Cumulative Update (KB3189866), I had the same problem on one of the 8 machines I work on at home. I downloaded the manual installer from the MS Download Catalog instead, and that worked fine. Find it here: Search results for "KB3189866" Grab the x64 or x86 (32-bit) version as your current install dictates [Note the 32-bit version is not labeled as such, it's the third entry in the list with a size of 255.4 MB.]. Hopefully, this will work for you as it did for me.
HTH,
--Ed--
Tried a number of fixes before I came across this link that was easy and worked for me. Fix Windows 10 Anniversary Update Stuck at 99% - YouTube
Here, lets actually make this issue "Solved"
It seems as though this issue can be experienced when you are upgrading from Windows 7 to Windows 10 Anniversary Edition. (Previous Windows 10 editions did not seem to experience this problem) And it can also happen when you are already on Windows 10, and updating to Anniversary Edition. (My build is 10240)
Lets just say, before upgrading to the Anniversary Edition, disable and stop the Windows Update service
(start>run>services.msc and look for Windows Update)
Windows 7 users, if your upgrade is sitting at 99% or it was moving along steadily and all of a sudden has hit the brakes (this is what mine did when it reached 82% and started to crawl) you can perform this fix and the upgrade will complete.
Windows 10 users, maybe you will have different luck. But for myself I could not get the Windows Update service to stop successfully. (Received a timeout error) but a restart and disable/stop of Windows Update service before running the upgrade went with out a hitch.
Good luck
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