Microsoft has identified what initially appears to be a mild, nay, arm-wavingly alarming issue with the recent Windows 11 preview build. Namely, installing this build may cause "devices to reboot repeatedly" and "require a recovery operation to restore normal use." [The issue appears to affect only virtual Windows environments that installed the optional KB5039302 update on June 26. This update is a preview build, which is essentially the bulk of the July update packaged for optional early download.

Thankfully, Microsoft discovered this issue prior to the patch scheduled for July 9. Had this update been released, some virtual Windows environments (most likely enterprise machines) might have failed to boot or restarted repeatedly. However, Microsoft said that the update "is currently only paused for devices affected by the issue" and "may not be available for Hyper-V virtual machines running on hosts utilizing certain processor types."

To be clear, this seems to be an issue only for virtualized Windows systems such as Microsoft Cloud PC and Azure Virtual Desktops, or localized virtual machines such as those running on VMWare or VirtualBox. In other words, there is no need to worry about physical PCs with Hyper-V enabled, and the problem seems to be only with virtual machines running on that hypervisor.

If you run Windows on a cloud PC or virtual machine and install this update, it can be uninstalled by undoing it from the Windows recovery environment after Windows has restarted multiple times Troubleshoot > Advanced Options > Uninstall Updates > Uninstall latest quality update and restart when prompted to restart.

The KB5039302 update has some nice improvements and fixes for non-virtualized Windows environments. Perhaps most relevant to PC gamers is a fix for an issue that prevents some GPUs from being idle when not in use. Also fixed is an issue related to high system CPU usage caused by the Windows Filtering Platform (WFP) driver used by firewalls, etc.

Thus, more CPU performance is freed up to feed framez, and power consumption for GPU users is reduced. That's right, bootloop. Sorry virtual desktop users!