Microsoft has acknowledged that the KB5058405 cumulative update released during May’s Patch Tuesday is causing startup failures on certain Windows 11 systems. Affected devices display 0xc0000098 recovery errors related to ACPI.sys, indicating that the operating system cannot load due to missing or corrupted files.

ACPI.sys serves as the Windows Advanced Configuration and Power Interface driver, a critical kernel-mode component responsible for power management and device configuration on systems with an ACPI BIOS.

“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,” Microsoft stated in an update to the Windows release health dashboard.

## Who Is Affected?

The issue primarily impacts enterprise environments, specifically:
– Azure Virtual Machines
– Azure Virtual Desktop
– On-premises virtual machines hosted on Citrix or Hyper-V

Microsoft has clarified that home users running Windows Home or Pro editions are unlikely to encounter these problems, as the affected virtual machines are predominantly used in IT environments.

## Current Status

Microsoft’s engineering team is actively investigating the issue and has promised to provide additional information as it becomes available.

This is the latest in a series of recent Windows update issues. Earlier this month, Microsoft resolved a problem blocking Windows 11 24H2 feature updates via Windows Server Update Services. The company also released emergency out-of-band updates to address a Windows 10 bug that forced affected PCs into BitLocker recovery after May’s security updates, and fixed a “latent code issue” that caused some devices to upgrade to Windows 11 automatically despite policies intended to block such upgrades.