Some laggards that still have some Windows Server 2012 virtual machines running got a bit of a nasty surprise last weekend. A number of them went into a boot loop. Apparently the November 2019 updates caused Windows Server 2012 reboot loop. Well, we have dealt with update issues before like here in Quick Fix Publish : VM won’t boot after October 2017 Updates for Windows Server 2016 and Windows 10 (KB4041691). No need to panic.
Not all Windows Server 2012 virtual machines were affected. We did not see any issues with Windows Server 2012 R2, 2016 or 2019. Well the symptom is a reboot loop and below I have a sequence of what it looked like visually.
So what caused this Windows Server 2012 reboot loop?
We turned of the virtual machines on which the November 2019 updates caused Windows Server 2012 reboot loop. We started them up again in “Safe mode” which completed successfully. Finally, we then did a normal reboot and that completed as well. All updates had been applied bar one. That was the 2019-11 Servicing Stack Update for Windows Server 2012 (KB4523208).
We manually installed it via Windows update and that succeeded.
When reading the information about this update https://www.catalog.update.microsoft.com/ScopedViewInline.aspx?updateid=5fa2a68f-e7cd-43c7-a48a-5e080472cb77 its states it need to be installed exclusively.
Maybe that was the root cause. It got deployed via WSUS with the other updates for November 2019.
Anyway, all is well now. I remind you that we have at least 2 ways of restoring those virtual machines. In case we had not been able to fix them. Have known good backups and a way to restore them people.
We fixed the issue and patched those servers completely. So all is well now. Except for the fact that they now , once more, have been urged to get of this operating system asap. You don’t go more than N-2 behind. It incurs operational overhead and risks. They did not test updates against this old server VM and got bitten. Technology debt without a plan is never worth it.