Microsoft reports 'an issue in which devices are failing to boot' after downloading the latest update

If you have downloaded January's KB5074109 Windows update and can't seem to get past boot, you aren't alone.

As reported by Windows Latest, Microsoft has updated users in a support document that it is "investigating customer reports of device boot failures following the January 2026 update and later updates."

The document is only accessible by Microsoft 365 business accounts, which does seem to imply that it's business devices that are typically affected by this boot problem. However...