[sfont]

This is my registry changes that has worked every time. Even when the install is set to kick off with the next reboot.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\OSUpgrade] "ReservationsAllowed"=dword:00000000 "KickoffDownload"=dword:00000000 "KickoffSource"=dword:00000000 "AllowOSUpgrade"=dword:00000000 "Refresh"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\OSUpgrade\State] "OSUpgradeState"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate] "DisableOSUpgrade"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Gwx] "DisableGwx"=dword:00000001

[tetraodonpuffer]

interesting, I knew about the last two, but not the OSUpgrade ones, did you find those are needed as well?

[sfont]

I copied the first part from a domain joined PC before a later update caused them to receive the upgrade prompt as well. It's kind of belt and suspenders so it doesn't harm but may not actually be needed.

[zxcvcxz]

On Linux we just close the update window.