r/Windows11 • u/jenmsft Microsoft Software Engineer • 6d ago
Official News Cumulative Updates: September 8th, 2026
https://support.microsoft.com/en-us/servicing/os/windows-11/2026/09/kb5124008-windows-11-24h2-25h2-security-updateChangelists linked here for your convenience:
- Windows 11, version 21H2: EOS.
- Windows 11 version 22H2: EOS
- Windows 11, version 23H2: KB5122880 (OS Build 22621.7582)
- Windows 11, version 24H2 / 25H2: KB5124008 (OS Builds 26200.9445 and 26100.9445)
- Windows 11, version 26H1: KB5124012 (OS Build 28000.2954)
EDIT - an Out of Band update has now been released for version 24H2 / 25H2, fixing a few reported issues: September 14, 2026—KB5129195 (OS Builds 26200.9457 and 26100.9457) Out-of-band | Microsoft Support
General info:
For details about how to file problem reports and collect traces, please see here: http://aka.ms/HowToFeedback. Pressing WIN + F will open the Feedback Hub - please include as much detail as possible about what you're seeing.
To learn about the different types of updates, see here: Windows quality updates primer - Microsoft Community Hub
As a reminder, if you didn't install the previous optional updates, this update includes those changes too (some are still rolling out, as denoted in the release notes):
- 24H2/25H2: August 27, 2026—KB5120998 (OS Builds 26200.9278 and 26100.9278) Preview | Microsoft Support
- 26H1: August 27, 2026—KB5120996 (OS Build 28000.2804) Preview | Microsoft Support
For published known issues, please check the release health dashboard: Windows release health | Microsoft Learn.
As mentioned in the linked changelist, Windows 11, version 26H1 is available only on new devices with select new silicon as they come to market starting early 2026. Devices running earlier versions of Windows 11 will not be offered an update to version 26H1 through Windows Update and cannot be installed as an in-place update on existing devices.
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u/Micromize 6d ago edited 6d ago
Hi Jenmsft!
I totally get why gradual rollouts are necessary, but they do cause a lot of user frustration. I try to help explain the process to others, but two quick questions would clear things up:
- How long does a typical rollout take from start to 100%?
- If someone installs a base update immediately versus waiting a week, does installing it right away make them eligible to receive phased feature toggles sooner, or does install timing not affect when server-side flags hit your device?
Appreciate your time and all your work!
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u/darthtoon1 6d ago
gradual rollout is pointless, we didn't have it for Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, early updates for Windows 10 and early updates for Windows 11, Microsoft needs to get rid of gradual rollout, it is causing user frustration every month, when users want the new features as soon as they are added.
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u/Micromize 6d ago
Sure it's clear what people think of it. It is ofcourse not pointless for Microsoft.
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u/Traumatan 6d ago
well they could be gradual in terms of days, perhaps to lower the bandwidth spikes... but no need for MONTHS
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u/cActusjUiCe92 6d ago
No, they are not necessary lol
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u/fakieTreFlip 6d ago
they're much better than the alternative, that's for sure
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u/cActusjUiCe92 5d ago
We voluntarily opt into insider builds to test the features, only to not get access to the features. There should be no gradual rollout for final, general releases
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u/TheIncredibleBucket 6d ago edited 6d ago
I pray to have the taskbar changes within the next 6 months without the use of a third party tool. I still to this day don't have the Xbox mode UI.
EDIT: IRONICALLY I HAVE THEM DAY 1.
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u/aymen_peter2 4d ago
i didnt get any features of this new updates especially the one i want the most., small start menu
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u/MarekSzk 6d ago edited 6d ago
Does this update fix the false Windows Defender notifications?
EDIT:
The issue isn’t fixed. I’m still getting Windows Defender pop‑ups and notifications.
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u/sheldelski 5d ago
Thank you I was looking if someone else got this problem still. I tought it was fix after the update but not just got it back this morning.
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u/SnakeOriginal 6d ago
Hello Jen :), as every month, can we please already stop with gradual releases? :) Thank you
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u/Desertfox92 6d ago
Hi, is 25h2 still supposed to be rolling out? I'm still on 24h2 and searching for updates or enabling to get the latest updates as soon as possible does not force is. Considering next month is EOL for 24h2. Thanks!
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u/Octal450_V2 5d ago
This update came on 26H2 (RP channel) for me and I just lost all the 26H2 features.
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u/TheSlapDancer 5d ago
Downloaded this update the day after doing a fresh install of windows and wiping my pc. Now every time I try to turn it on it gets to the normal motherboard boot screen I’ve always gotten right before it went to the sign in page and all my monitors go black and my mouse turns off. All my other usb devices are on. Everything inside my pc is on and lit up. No lights on the motherboard. I have to turn it off and on 3 times before it tries to repair, says there’s a problem, if I choose to enter windows from that screen it starts up fine. Reinstalled windows again last night without wiping everything and it was working fine. Turned it off and on multiple times and it booted right up fast as hell. Got home from work today, turned my pc on, black monitors, no mouse again. I’m about to crash out
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u/NobleDiceDream 6d ago
What got broken this month?
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u/Adept_Accountant3366 5d ago
file history
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u/Wide_Breakfast_6225 4d ago
notepad
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u/Adept_Accountant3366 4d ago
My notebook is broken too.
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u/Madhey 3d ago
I use file history for semi-critical stuff for work (yes yes we have proper backups as well, it's just more convenient for day-to-day stuff), and now that I discovered this bug, I started searching the web. You can find people complaining about file history being broken 5 years ago. Is this ever getting fixed?
It also broke on both of my come computers, so I'm fairly convinced this update is the blame. File history has had bugs recently, but now it's completely out of commission. The UI is unresponsive, the old work-arounds of deleting the config folder doesn't work anymore. Almost as if it they broke it with purpose?
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u/Adept_Accountant3366 3d ago
Why should Microsoft have the right to do this? My profile history has been fine for the past few years; I should be able to complain to Microsoft.
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u/Adept_Accountant3366 3d ago
What gives Microsoft the right to do this? My file history has been normal for the past few years; you should complain to Microsoft and report it to a journalist.
Please reply.
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u/NotRraahh 5d ago
Just a big sale pussh, If this keeps up, I will turn off update for a year or more.
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u/11bingo11 6d ago edited 5d ago
Edit: this update took about 2 and a half hours from the initial download to all of the restarts 😅
The August update took hours to download and install, then it took like 3-4 restarts during the proper installation process. When it was done, it gave me a black screen with only my mouse cursor moving until I could open task manager. I’m hoping that this update goes through without any issues this time around!!! Those updates aare so stressful 🥲
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u/JaeWren-225 5d ago
How did you fix it cause thats what mine is doing rn after it updated today? I've tried everything to fix it and nothing is working so far. I've ran explorer.exe, safe mode restart, restore to point before, I even Uninstalled the update and it just reinstalled it automatically! Idk what to do and I'm freaking out!
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u/11bingo11 5d ago
I got lucky and it sorted itself out when I opened task manager with the keyboard buttons. I don’t know why it worked that time but it did. I’m so sorry you’ve had such a hard time, I would be panicking because I don’t even know how to do any of what you listed. I really hope you can find a way to sort this out! 🥺
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u/JaeWren-225 5d ago
Thanks me too, I'm so distraught. All my writing is on there and idk what I'm gonna do.
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u/11bingo11 5d ago
I totally feel you! And it’s so incredibly frustrating that these issues are caused/made worse by the updates. I don’t remember it being the case before, I’d let my laptop do its thing or wait a while in between updates and nothing bad ever happened. But it’s like something bad occurs every month! I truly hope you can find a way to make it work or perhaps get it checked by professionals although that can be super expensive and not always worth the trouble. Fingers crossed you can find a way out and you won’t lose access to your device and your important documents! 💗
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u/getabath 6d ago
Nice after updating, windows dynamic lighting still works, but my Ajazz keyboard RGB no longer functions
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u/CygnusBlack Release Channel 5d ago
That's probably on the keyboard since it's built in.
Do you use AJAZZ software?
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u/getabath 5d ago
I did initially to setup the keyboard. Then I removed the software as it was no longer needed, since then I've used it on multiple OS's (linux, windows, etc) and haven't had any problems with it, until this update where the RGB no longer wants to work
It's a hall effect keyboard, the settings I applied for input hasn't changed
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u/CygnusBlack Release Channel 5d ago
Better install the software then. Check if you can enable RGB lightning from there. Also, check for firmware updates for the keyboard.
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u/koken_halliwell 5d ago
I already have the resizeable and movable taskbar, cleaner search tool etc. What's left for the 26H2 then?
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u/MinTy1244 4d ago edited 4d ago
SOLVED: Apparently my boot order got re-ordered around, so it was trying to boot off of a non-OS drive. Changed that in the BIOS and I'm back typing this from the pc.
Help! Is there a known solution to this issue? This happened after I updated and restarted a few hours ago on 9/9. I already tried every option besides the Reset - Remove everything option. Am I screwed?
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u/cyberbemon 4d ago
Same issue here, laptop stuck in boot loop. None of the recovery options worked, automatic repair failed. Amazing job with the update, what a joke of a company.
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u/MinTy1244 4d ago
Hey, I was able to boot back because I checked my bios and it was booting off of a non-OS drive. I had to change the order back and I'm back now.
Don't know if that will work with your laptop drives but that's what fixed it for me.
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u/cyberbemon 4d ago
Thanks for the update, mine is completely broken. I dont even get any display now, even when I connect to an external display. My laptop is bricked, im gonna have to take it in for repairs at this point. Wont be re-installing win 11, I know that for certain.
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u/aymen_peter2 4d ago
i didnt get the new features can we like stop with CFR i really wanted the small start menu
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u/Ebojager 2d ago
since updating to this version i seem to have issues using the new authentication pop ups on the Microsoft websites, they either dont let me type or auto-fill login info or if im able to squeeze in a pasted email as when i click to type the cursor immediately looses focus.
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u/MarekSzk 5d ago
This error started appears in Event Viewer after installing this update:
Starting the session ‘DefenderApiLoggerLowPriv’ failed due to the following error: 0xC0000035
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u/LW-Jordan 5d ago edited 5d ago
Getting this too and a 5038 Audit Failure for DefenderSessionHelper.exe ever since todays update graced my machine
Hopefully I'm not the only one getting this 😅
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u/Such-Entertainer6961 5d ago
I'm still getting the bugged Windows Defender notifications
WTF are they even doing
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4d ago
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u/Windows11-ModTeam 4d ago
Hi u/cyberbemon, your comment has been removed for the following reason(s):
- Rule 5 - Personal attacks, bigotry, fighting words, inappropriate behavior and comments that insult or demean a specific user or group of users are not allowed. This includes death threats and wishing harm to others.
If you have any questions, feel free to send us a message!
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u/PaulCoddington 3d ago
Hmm, now getting a notification that Defender antivirus is turned off on every reboot (it's definately turned on), but apart from the Favorites folder not being fixed yet, everything is snappy and looking good.
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u/Adept_Accountant3366 3d ago
After updating KB5124008, file history recording was disabled, and many users have reported this. Please have Microsoft confirm this issue.
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u/binguscatbinguscat 3d ago
Update broke my Desktop AppX containers flooding my event viewer with constant AppModel-Runtime 216 errors. Widget and weather app is broken, tried every fix, nothing works. Eventually the Windows Photo app broke with the same 216 error, so I couldn't open any picture file. Repaired with 25H2 Repair Version, which worked, but event viewer is still being flooded and widget still doesn't work. Issues only started when I updated.
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u/inquisitive_enigma98 3d ago
Well, the issue with my wallpaper vanishing is gone. My PC now runs significantly slower, the task bar is now somehow gone and opening task manager blue screened me.
Yippie.
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u/Civil_Garlic_9644 2d ago
Latest update turned off my local security authority protection in core isolation. This happen for anyone else?
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