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ZDNET’s key takeaways
- Microsoft has issued its second emergency patch of the month.
- The new patch fixes a bug that affects cloud-based services.
- But another bug is preventing some Windows PCs from booting up.
This year has got off to a rough start for Microsoft and Windows users, at least when it comes to bugs. The January 2026 update introduced a slew of glitches that the company is now trying to clean up. At the same time, new bugs keep popping up and plaguing users.
New emergency patch
On Saturday, Microsoft kicked off its second out-of-band emergency patch of the month. Dubbed KB5078127, this one fixes a problem introduced by the January Patch Tuesday update. Specifically, the update prevented Outlook and other apps from opening files from, or saving files to, cloud-based storage sites such as OneDrive and Dropbox. This meant that Outlook would fail to open for many people who stored their PST files on OneDrive.
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This emergency patch includes the first out-of-band patch issued on Jan. 17 to fix issues with remote connections to Windows Cloud devices and with Secure Launch. It also carries the security fixes and improvements from the Jan. 13 update, but hopefully without the bugs.
If you are running into trouble trying to open or save files with OneDrive, Dropbox, or other cloud sites, you may want to install this latest patch and keep your fingers crossed that it doesn’t introduce any new bugs. Head to Settings and Windows Update, and you should find the KB5078127 update waiting for you. I spotted it on my Windows 11 PC today. Otherwise, click the button to check for updates, and it will pop up. Allow the update to install, after which you’ll have to reboot your PC.
The bugfest is far from over
While Microsoft has been fixing bugs caused by the Patch Tuesday update, another glitch has surfaced.
Also caused by the January update, this one is preventing a limited number of Windows computers from booting up, as spotted by AskWoody. Impacting Windows 11 25H2 and 24H2, the bug triggers a black screen upon boot-up and displays a stop code pointing to an unmountable boot volume.
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If you’re affected, you’re unable to launch Windows and may have to use Windows Recovery to restore your environment. Microsoft said that it is investigating the problem but clearly has no fix at this point.
“Microsoft has received a limited number of reports of an issue in which devices are failing to boot with stop code ‘UNMOUNTABLE_BOOT_VOLUME’ after installing the January 2026 Windows security update released January 13, 2026, and later updates,” the company said in a support note. “Affected devices show a black screen with the message ‘Your device ran into a problem and needs a restart. You can restart.’ At this stage, the device cannot complete startup and requires manual recovery steps.”
Quality control question
Some of these bugs are isolated to specific hardware and software configurations. And with all the variations out there, it’s difficult for Microsoft to test for every possible combination. The company has also responded relatively quickly to squash these new bugs. But that doesn’t leave it off the hook, not by a long shot.
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Pushing out an update that fixes some bugs only to create new ones begs the question of what type of quality control is in place at Microsoft and how it expects people to trust it. With only one supported client version of Windows, the onus has been on the company to make sure the OS is as stable and reliable as possible. Clearly, that’s not happening, not when regular Windows updates that are supposed to fix problems end up causing new ones.
