Forced update to anniversary

I have a dualboot laptop that I mostly use with Linux. In the second partition I installed Win10 professional rather than home for the explicit reason that I wanted to block all updates (after having it update once), reason being that I didn't want to be bothered by constant reminders and reboots. The partition is imaged and I don't use it much anyway, so I don't fear malware - anything that infects it would be easily wiped by a simple reimage.

So I disabled the updates via the policy editor, and it's been working hassle-free for months

However, today I booted it up and started working, and unexpectedly a message appeared telling me that it would reboot in a few minutes to apply an update - it didn't ask me for a time or authorisation and wouldn't let me delay it, which is infuriating enough in its own right. And reboot it did, taking its damn time applying the update too, and rebooted again, and then I had to reapply all the system settings that had been reset by the anniversary update, and I lost a morning's work.

I appear civil now because several hours have passed and I've processed the irritation, but you better believe that the curses I uttered while this was happening were long and colourful.

I've now disabled the updates by murdering the windows update service, which I should have done to begin with, but I'm wondering - is this a known occurrence? Does Microsoft simply ignore your update settings to force the anniversary update now?

The next time I reimage I'll be sticking the update servers in the hosts file just for good measure, but if Microsoft is ignoring my desire for hassle-free productivity *that* much I'm thinking perhaps I should wipe the Windows partition and set it back up as a virtual machine that I'd set up once and reset upon every reboot.

TL;DR: Win10 pro with disabled updates updated anyway wasting several hours of my time, am pissed about it and trying to figure out where to place the blame.

There is no normal setting in Windows 10 Pro to disable updates. The option available in normal settings is to DEFER updates.

Defer: put off (an action or event) to a later time; postpone.

alphanumeric said:

It's Defer feature updates, isn't it? Which just stops you from updating to a new build. It won't stop regular updates.

To actually have control over updates with Windows 10 Pro, it has to be setup for Windows Update for Business. Basically you need to be running Pro on a Corporate network for that.

and I think it only defers the major upgrades until they hit LTSB.