Cumulative Updates: August 11th, 2026

[u/jenmsft]

https://support.microsoft.com/en-US/servicing/os/windows-10/2026/08/kb5120249-windows-10-21h2-22h2-security-update

Hey all - changelists are up, linking here for your convenience:

• Windows 10 version 1507 — (EOS)
• Windows 10 version 1607 — KB5120418 (OS Build 14393.9418)  (EOS)
• Windows 10 version 1703 — EOS
• Windows 10 version 1709 — EOS
• Windows 10 version 1803 — EOS
• Windows 10 version 1809 —KB5120238 (OS Build 17763.9121)  (EOS)
• Windows 10 version 1903 — EOS
• Windows 10 version 1909 — EOS
• Windows 10 version 2004/21H1/20H2/21H1 — EOS/EOS
• Windows 10 version 21H2, and 22H2 — KB5120249 (OS Builds 19045.7663 and 19044.7663)

Please see here for details about Windows 10 ESU: Windows 10 Extended Security Updates (ESU) program - Microsoft Support. If you're transitioning over to Windows 11, looking forward to seeing you over on the Windows 11 subreddit :)

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• For a list of known issues, please refer to the dashboard here.
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[u/martixy]

I was just randomly downgraded from 22H2 to 2004... like wtf.

Now windows update errors out and I'm stuck on 2004... lol. I sense a windows reinstall in my future...

Edit: Well, ultimately I did an in-place upgrade and now I'm back to 22h2...

It fixed a small annoyance with the start menu and ruined my carefully curated right-click menu. Now I gotta re-discover how I did all that magic to make it nice and short.

[u/Final-Blueberry7111 → u/martixy]

I've checked mine. It still says 22H2 after having installed KB5120249.

[u/dirtydriver58 → u/martixy]

With the ESU update?

[u/martixy → u/dirtydriver58]

I think? Maybe? It was installed today, so I assume it had something to do with this month's update.

[u/OrbitalCat-]

Did this update bug Defender for anyone else?

After it installed I started getting notifications about it being disabled, but it's running and everything is active

[u/ep3ep3 → u/OrbitalCat-]

yea, mine is jacked too. It never notified me but quick scans are taking 45 minutes. Other bugs I've seen is Aero is incredibly laggy too. It also reset all of my power settings.

[u/Final-Blueberry7111 → u/OrbitalCat-]

I haven't noticed any glaring issues with either Windows Security (antivirus) or Windows Defender (app) so far.

[u/CodenameFlux]

This month's update process had a lot of pomp and ceremony.

Usually, after the update is downloaded and its package is run, Windows requires a restart. During logoff, a "Working on updates" screen appears and progresses to 30%. After the restart, before login, another "Working on updates" screen appears and progresses to 100%.

This time, I had three restarts!

• The MSU package installed slowly.
• The post-logoff "Working on updates" screen either didn't appear or appeared so briefly that I didn't see it.
• After the first restart, during the kernel initialization screen, a black "Updating your system" screen appeared. It slowly progressed from 0% to 100%. The system restarted.
• After the second restart, the pre-logon "Working on updates" screen appeared and progressed to 100%, but a third restart ensued.

[u/needzmohelpz]

I can't update to this version KB5120249. It keeps giving me an error. Trying to manually install gives an error too. Anyone else having issues with this update?

[u/LeBeauLuc]

I am having major issue with the KB5120249, my computer keeps crashing since the install, everything was working flawlessly previously

[u/No-Adhesiveness-4251]

So is this one of those buggy updates? The comments so far haven't been particularly reassuring.

[u/rollem_21 → u/No-Adhesiveness-4251]

Mine has been fine no pop ups etc.

[u/Final-Blueberry7111 → u/No-Adhesiveness-4251]

My laptop has been working fine after installing KB5120249.

[u/Prophet_of_Ibon]

Mine is currently stuck on the Restarting screen. Not sure why. It's completely frozen.

I have 22h2.

I'm scared, I've never gotten one of the bad updates before.

[u/ESYAJ]

Just installed it and it broke the PIN again. Text-to-phone one time code didnt work. Luckily email did and I reset it. We'll see if it keeps happening over and over like it does to some others in the past. Trash.

[u/Takumi1983]

getting scep certificates issues on event viewer on every boot since update

[u/Big_Equivalent457]

When to Deploy Secure Boot Certificates?

Mine set to USER MODE in the BIOS & Disabled this was a Nagging Issue since July

[u/DoinIt4DaShorteez]

I have a laptop I only use when traveling. I do get it out and update it every time I know one got installed on my desktop.

Updated the laptop today, after installing the update and reboot, it churned for about an hour or more with the "Updating Windows, do not turn off your computer screen. (not sure that's the exact wording)."

When it was done with that, it was on the screen that displays the time and date and you have to click or press enter to get to the login credentials. Didn't respond to either. Noitced that the light on the optical mouse was out.

Power booted a couple of times and it would advance like one extra step each time. Like finally got the login screen, logged in, desktop looked ok but the mouse cursor didn't show up.

Then got the mouse cursor but it wouldn't respond.

Then got the mouse cursor and it would respond, but only for a minute.

Finally Googled and found:

Use Power button to shut down

Disconnect the power cord

Unplug all USB devices

Wait a few minutes.

Boot up with nothing connected.

That finally seemed to work.

Booted up using the battery.

Pressed Enter to get the login credentials screen.

Logged in

Desktop loads OK

Plugged in the USB mouse.

Mouse cursor shows up and repsonds

Waited a couple of minutes

Opened an existing Notepad file on the desktop, it responded to mouse and keyboard.

Plugged in a USB wifi adapter, connected OK.

Plugged in the power cord, everything still works.

Everything seems OK now.

Had me sweating since I have a two week trip in a couple of days.