V – KB5009624 prevents your VMs from starting (2012R2)

Today I made updates on my lab ‘and as a result my VMs (virtual machines) did not start anymore!

Being accustomed to the side effects of Windows updates I immediately understood that it had to come from a failed update …

This update concerns only Windows 2012 R2 version !

What is KB5009624

Newer versions like Windows Server 2016 2019 or the latest Windows Server 2022 are not concerned !

The update detail is available here

The solution while waiting for a fix is ​​to uninstall KB5009624.

Unfortunately this update “breaks” the functionality of the Hyper-V hypervisor. Indeed, virtual servers can no longer start after installing the update.

Uninstallation from Programs and Features

You have several solutions like the command line in Powershell or the “Programs and Features” panel. You must then search for the KB number in the search bar.

programs and functions menus

Enter the KB number at the top right.

Once uninstalled you must restart your server.

Command line uninstallation

You have to open the command prompt as administrator and then enter the following command:

wusa /uninstall /kb:5009624

Once the 2012R2 server has restarted your virtual machines should restart.