Microsoft’s October 2023 patch day is proving to be quite problematic for system administrators Windows Server 2022 e 2019: After installing updates distributed this month through Windows Update and other Microsoft channels, Hyper-V machines refuse to boot normally displaying a series of error messages.
The problem can be traced back to the presence of update packages KB5031361 and KB5031364intended for Windows Server 2019 and Windows Server 2022 systems respectively.
The appearance of errors such as “Failed to start virtual machine TOOLS. Error: ‘TOOLS’ failed to start“, “Incorrect function“, “Unable to open attachment vhdx_path” is a clear indication of the problem.
How to fix the problem in Windows Server and get Hyper-V machines booting again
Microsoft technicians have not yet officially confirmed the existence of the problem. However, IT administrators express the need to get back to running the virtual machines set on Windows Server 2019 and 2022.
Waiting for a patch official, the only way to overcome the problem is to uninstall the October 2023 update package. To do this, just type cmd in the Windows Server search box then choose Run as administrator. When the window appears command prompt the following instructions must be given:
wusa /uninstall /kb:5031364
wusa /uninstall /kb:5031361
Depending on the version of Windows Server you are using, the command Windows Update Standalone Installer (SO), which allows you to install and remove software packages using APIs Windows Update Agent.
The KB5031364 update had already highlighted compatibility problems with installations of VMware ESXi, another solution for virtualization. In the first version of this bulletin, in fact, Microsoft had confirmed the problem. The notice in question has now been removed. It is easy to hypothesize that, at this point, the support document is further updated with the reference to the failure to start Hyper-V virtual machines.