Windows Server 2019/2022 Restart Loop (KB5009557 and KB5009555)

Microsoft definitely has a series of problems with its Windows Updates , I recently explained to you how to troubleshoot your Hyper-V hypervisor on Windows 2012R2.

The operating system concerned was very different but two rather recent systems are now affected. Windows Server 2019 and the latest version of Windows Server 2022

The impacts of KB5009557 and KB5009555

Server reboot

The impact is critical, among the effects observed are the “reboot” servers. While going through the server logs I noticed that there were a lot of “kernel errors” related to the LASS.exe process

It seems that updates are freaking out this process. The server processor ramps up to cause a nice blue screen (BSOD) and then force a restart of the server.

So the “good” news is that this bug affects only domain controllers (servers with an active directory).

windows server 2022 desktop
Desktop of a Windows Server 2022 server.

Loss of REFS partitions

REFS is a partition system intended to replace NTFS. You cannot install an operating system on it, but you can store your data there.

The protocol is also much more efficient since Windows Server 2016

In short, it allows the use of technologies such as “Fast Clone” anddramatically speed up processing time of VHDX files (Hyper-V VM file).

For users of Veeam software you should feel a difference in backup time.

Updates also affect REFS volumes, indeed it is impossible to access it.

There are currently no fixes, the only solution is to uninstall KB5009557 and KB5009555

  • Windows Server 2019 is the KB5009557
  • Windows Server 2022 is the KB5009555

You can do it from programs and features

programs and functions menus

The KB search can be done at the top right.

Another solution is the command prompt in administrator mode.

wusa /uninstall /kb:numero-kb

For Windows Server 2019 KB009557

wusa /uninstall /kb:5009557

For Windows Server 2022 KB009555

wusa /uninstall /kb:5009555

Once the KB has been uninstalled, you must restart your servers.