Microsoft has released an urgent update to fix a serious problem that left some Windows 11 PCs unable to start after the installation of the KB5058405 May 2025 security update.
Affected computers would crash during start-up, displaying a 0xc0000098 error tied to a system file called ACPI.sys — a Windows driver essential for power management and device configuration via the Advanced Configuration and Power Interface. The error message warned the users that the operating system couldn’t be loaded and needed to be repaired.
Your PC/Device needs to be repaired The operating system couldn't be loaded because a required file is missing or contains errors. File: ACPI.sys Error code: 0xc0000098
Last Thursday, Microsoft acknowledged the issue, saying it mainly affects virtual environments, with limited cases on physical devices. Impacted systems include: Azure Virtual Machines, Azure Virtual Desktop, and on-premises VMs hosted on Citrix or Hyper-V. However, if you have PCs running Windows Home or Pro editions in home environments, you likely won’t run into this issue.
“We are investigating reports of the May 13, 2025 Windows security update (KB5058405) failing to install on some Windows 11, version 22H2 and 23H2 devices,” the company wrote on the Windows release health dashboard on Thursday.
The Fix from Microsoft
To fix the installation and boot problem, Microsoft released the KB5062170 non-security out-of-band (OOB) update over the weekend, which is available now from the Microsoft Update Catalog. It’s a non-security patch and needs to be installed manually.
For organizations that are already affected by the issue, Microsoft recommends that they use the built-in Azure repair tools to get things back up and running.
“We recommend using Azure Virtual Machine repair commands as a workaround for Azure customers who have already applied the May 2025 Windows security update and are experiencing this issue,” the company noted in a weekend update to the Windows release health dashboard.
“If you have not yet deployed the May 2025 Windows security update (KB5058405) and your environment includes devices running in a virtual desktop infrastructure on Windows 11, versions 22H2 and 23H2, we recommend you apply the OOB update instead.”
