Windows update KB2919355 fails to install - Error code 800F0922

Short version: check with Linux gparted that 'boot, efi' flag is on EFI partition and if not set it there (and only there). No disk backup necessary.

Long version: I had laptop with Win 8 UEFI preinstalled (since then upgraded to Win 10), added Ubuntu and fixed boot problems with boot-repair. That was a long time ago and I cannot recall exact steps but the result was that 'boot, efi' flag was on Ubuntu system partition. Everything worked fine apart from 800F0922 error on some Windows updates. No other advice from Internet helped but moving 'boot, efi' flag to EFI partition solved this problem immediately.

No problem! Here are the steps I used to extend my System Reserved partition and successfully install the update.

1. I first selected my main partition (C:) and clicked Move/Resize then subtracted 650MB from the main partition to leave about 650MB in Unallocated Space as shown in the picture below. 650MB may not be necessary, I only chose this amount so that my System Reserved Partition would have an even 1GB of space.
2. I then selected the System Reserved Partition and clicked Move/Resize again and increased the size by 650MB until there was no Unallocated Space remaining and the size of the drive was about 1GB.
3. You will need to click the Apply button (grayed out in the screenshot) after completing these actions and your computer will restart so that the drive will be free for operations.
4. I was then able to install the update without any problem. Hope this helps someone else too! Please mark this as the answer if it helps you!

I don't have a cisco VPN.  I'm trying to understand which solution actually fixed the error.  Also, I would think Microsoft wouldn't require people to invoke third party software to tweak their computer settings to allow a general update to be successfully installed.  I would assume they are trying to address this in the background to those who are not power users.

I was able to install KB2919355 after 8000F0922 error. But in my case there were no problems with system reserved partition. It turned out, installer could not execute "netcfg" command. Root cause was a Cisco VPN client. When I deleted VPN client, update installed normally.

I had the same problem as alexeyI. In fact, my PC doesn't even have a "System Reserved" partition (it's optional--used by BitLocker and perhaps other system features). 

I looked in the Event Viewer (Windows Logs > Application) and saw that an APPCRASH event was logged by the source "Windows Error Reporting" at the same time that the KB2919355 update reported that it failed.  In the "Problem Signature" section of the event, P1=netcfg.exe and P4=netcfgx.dll.  So it was, as alexeyI pointed out, that the update was encountering an error when running netcfg.  I also had Cisco VPN installed, so I uninstalled it and rebooted. After that I used Windows Update to apply KB2919355 again, and it succeeded without issue.

Cisco VPN has caused problems in the past in various other ways, and it often behaves in non-standard ways, such as automatically attempting to resinstall itself if a desktop shortcut to it is deleted etc. I wish Cisco would get their act together in regards to this program.

I was able to install KB2919355 after 8000F0922 error. But in my case there were no problems with system reserved partition. It turned out, installer could not execute "netcfg" command. Root cause was a Cisco VPN client. When I deleted VPN client, update installed normally.