Windows Update KB5120998 (August 27, 2026)

Question

Windows Update KB5120998 (August 27, 2026)

Colin Warmbrodt 0

I'm trying to install the KB5120998 update that was released August 27, but am having a bit of trouble. Even though it downloaded, the download automatically restarts, and I'm prompted to press the "check for updates" button, but to no avail. Even at that, though, I'm pretty wary about actually installing it, 'cause I've seen some reports that it's "reverting mouse settings," which is a bit concerning. Is there any way to fix this?

Stand 0 Reputation points

2026-09-07T00:30:26.0433333+00:00

I was having issues with this update as well the other day or whenever it came out last week or something or another, and actually called a Microsoft technician that prowled through my laptop trying to figure out why! and do all this and that to try to get it to install on my laptop, he was not knowledgeable of the issues that it causes on certain devices or whatever on the PC Windows 11! He should have known better! But I had to Google it the other day just to find out exactly why it wouldn't install on my machine! because it's bugged, and Microsoft has probably stopped it from installing on my devices now because it's bugged! Microsoft needs to debrief their representatives a little more instead of them just prowling all over someone's PC and prowling through their settings and switching stuff around that they shouldn't be touching! It took me literally one day 16 hours to prowl through my laptop and figure out exactly what he did wrong! I wasn't quite paying attention because I thought he knew what he was doing, and he was going really fast going through this window setting and that window setting, prowling through Windows 32 files deleting this deleting that! Nothing worked and I finally disconnected him from my PC and he called me and asked me what happened and asked me if I wanted him to reconnect I was like no I'll figure it out on my own and I hung up on him! I eventually fixed my PC but that preview update won't install and I know why now! Because it's bugged, and he should have knew that in the beginning to begin with but the representative didn't, he tried to repair my windows operating system Windows 11 dual complete repair of it, and in the process of him doing that dos repair thingy with the black screen and the lettering and stuff I don't know what it's called I'm tired, and it was at 63% and it took 2 hours to complete but in the process of that he was trying to reinstall Windows with a downloaded ISO that he downloaded onto my desktop and unzipped it into a folder using my 7z program! He tried running the setup wizard with it while the other thing was running, you don't run both like that at the same time it takes up more resources but he did it anyways! And then the Windows installation failed he was just going to do a basic reset and reset all the system files to fresh, and it showed me it wouldn't delete any of my system settings or anything, but that failed like I said, it said my computer wasn't compatible with Windows 11! Which I know it is because my Acer natural 5 I bought in 2020 came up for the windows 11 update about a year later or so you guys know more than I do about the day it came out, but people in the Acer community stated that that version of Windows 11 was bugging out their bios in the bios settings, so I didn't download it or they were having some kind of issues it was bugging out their computers and it was making it to where it bricked and nothing worked and they had to completely reinstall Windows and that didn't work because the BIOS was fried or something stupid or overwritten, so I didn't update it, I waited it a long time about a year or two before I decided to actually install Windows 11 on my rig, I wanted to wait for a more stable version to come out and so it did! I just looked at my Windows update history right here it states that I installed Windows 11 version 22 H2 on December the 12th of 2023! And it ran perfect I was a little skeptical about installing it because of all the issues that other Acer nitro users went through, and it ran fine and it's been running fine and my windows 11 version now is 25H2, my security patch update was successfully installed on August 12th of 2026, and haven't had any issues at all with Windows 11 home, so why doesn't Windows 11 home install from the ISO on my PC it says it's incompatible? I'm rambling sorry I have a lot of questions that aren't answered and representatives probably through my PC messing it up trying to anyways!

2 answers

Your answer

Answer 1

DaveM121 928.6K Independent Advisor

You are correct, there are some widely reported bugs in the KB5120998 optional preview update that was released at the end of August, including black desktop backgrounds and mouse cursor problems.

KB5120998 is an optional preview update, it is basically an early beta release of the September update.

The optional preview updates can be hard to install sometimes and there is no need to install the optional preview updates.

If that update is continually failing, below that update is a switch to 'Get the latest updates as soon as they are released', disable that option and restart your PC, that will stop the optional preview update continually trying to install and wait for the full September update to be released, Microsoft should have the bugs in that update fixed before the full update is released

Adam J. Marshall 11,031 Reputation points MVP

2026-09-01T18:46:49.22+00:00

I'm going to comment that your view of this optional preview update being a beta release is not correct. All Optional Preview updates are 100% production ready, and tested updates. The only reason why they are 'preview' is so that IT people can 'test' the update functionality on a subset of their devices and see what new features it brings so that they can plan accordingly. The fact that there are bugs reported in this update is coincidental to it being a preview update.
Kevin White 0 Reputation points

2026-09-04T02:10:59.8333333+00:00

Thank you Dave. I've been trying to install this update for hours it's annoying as possible. Adam you can say it's production ready and tested but many of us can assure you that it doesn't work.
Adam J. Marshall 11,031 Reputation points MVP

2026-09-04T10:18:40.5566667+00:00

I'm not saying there isn't a bug with it, but there are specific things within those environments that are causing the issues.

I have it on my system and I haven't had any issues what-so-ever.

Answer 2

KB5120998 is a Preview update and it is offered as an optional update. It is not required to keep Windows secure, so if there is concern about stability, it can be skipped for now and the fixes will roll into a later security update.

For the install loop, try these supported steps first:

Make sure the PC is connected to the internet and plugged in.
Go to Start > Settings > Windows Update > Check for updates.
For this specific preview release, also check Start > Settings > Windows Update > Advanced options > Optional updates and install it from there if it appears.
If Windows Update keeps restarting the download, install it manually from the Microsoft Update Catalog:
- Open the KB5120998 catalog entry.
- Select the package that matches the device architecture (x64 or arm64).
- Download all MSU files for KB5120998 into the same folder, such as C:\Packages.
- Install with an elevated Command Prompt using: DISM /Online /Add-Package /PackagePath:c:\packages\windows11.0-KB5120998-x64_- Download link will be available soon
- Or use an elevated PowerShell prompt: Add-WindowsPackage -Online -PackagePath "c:\packages\windows11.0-KB5120998-x64_- Download link will be available soon"
- If the device is arm64, use the arm64 package instead.
If installing the MSU files individually, they must be installed in order:
1. windows11.0-kb5043080-x64_- Download link will be available soon
2. windows11.0-KB5120998-x64_- Download link will be available soon

About the mouse-setting concern: the available context for KB5120998 does not list that issue. A different August 27, 2026 preview update, KB5120996, specifically says it improves touchpad reliability and that Microsoft is not currently aware of any issues with that update. No matching known issue is provided here for KB5120998.

If the goal is the safest path, the practical option is to wait and skip KB5120998 for now, since preview updates are optional.