- Windows 10 has a new update as part of Microsoft’s extended support
- It reportedly breaks StartIsBack, a popular customization app
- The December patch also apparently causes issues with multiple monitors and performance slowdown in some areas
Windows 10 has a new update as part of Microsoft’s extended support scheme, but there are reports of this latest release causing trouble for some users.
A notable issue that’s been raised in multiple reports about the December update for Windows 10 (patch KB5071546) is that it breaks a popular customization app that revamps the Start menu.
That app is StartIsBack, and according to said reports on Reddit and X (see below), it’s failing to work completely, but only on some PCs, where users are facing a blank screen instead of the desktop.
The system is apparently still functioning behind the black screen, but obviously not being able to have the desktop rendered makes using Windows 10 very tricky (though you can still access interface elements via keyboard shortcuts).
The Windows 10 December 2025 ESU update seems to be incompatible with StartIsBack, at least on some machines. explorer crashes after startup with StartIsBack installed; starts only with those DLLs renamed. Mysteriously, explorer still works with StartIsBack on some machines.December 10, 2025
Another Reddit thread that contains a further complaint about StartIsBack highlights some other issues with this patch.
One Redditor observes that the December update meant their “wallpaper engine broke, wallpaper animations became choppy, task manager showed increased CPU spikes suddenly, [and] the UI started lagging.” This was cured by reverting away from the update, and another Windows 10 user confirms they suffered a similar problem.
There could be some minor gaming issues here, too, as another Redditor claims the update causes frame rate drops in Overwatch, and a further disgruntled gamer says it broke the Xbox app.
There’s another complaint on Reddit about the December update repeatedly trying to install itself, even though it’s already installed.
Add to that an apparent bug with multiple monitors whereby a pair of displays hooked up to the PC stopped working after KB5071546 had been installed, with the Windows 10 desktop apparently failing to load (again). Disabling one monitor fixes the problem, we’re told, as does removing the December update – and two other Redditors chime in to say they’ve experienced this exact same problem.
There are also scattered reports of the December update failing to install (for example, here’s one on Microsoft’s Tech Community hub).
Analysis: StartWasBack but the December update took it out
At the moment, we need to be cautious around these initial reports of bugs, some of which may be far from widespread. Still, it seems like there is something amiss with a few aspects of the December update for Windows 10, and certainly there’s a problem with StartIsBack (and potentially other similar Windows customization tools).
This isn’t uncommon, to be fair, as these kinds of apps tinker with bits of the underlying Windows interface, and when updates make changes, they can clash with the customized parts of the UI, causing Microsoft‘s OS to throw a hissy fit.
There is an apparent solution for the StartIsBack woes raised by one Redditor, InterestingKale3483, and that’s to simply install the latest version of the app (someone else verifies that this works). It could be tricky to resolve the situation seeing as those affected are facing a blank desktop, mind, but you can follow the advice in this post to remove the existing copy of StartIsBack, so you can get to a visible, working desktop – then install the latest version of the application.
What’s odd about all this is that I assumed Microsoft would only be patching security vulnerabilities at this point, so it’s not clear why stuff would get broken in this way. However, there is one change highlighted by Microsoft in the documentation for KB5071546, namely a tweak (security fix) for PowerShell 5.1, which could be the cause of the problems with StartIsBack (and other interface-related glitches, perhaps).
It’s worth noting that without Windows 10’s December update, you are missing some defenses against fresh possible exploits out there – so bear that in mind if you’re mulling over rolling back the upgrade.
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