I’m trying to figure out a strange issue that started very recently on my Lenovo Legion.

The laptop randomly goes to a black screen for a couple of seconds and then recovers. At first I thought it was an NVIDIA/Optimus or refresh-rate issue, but I started monitoring the Windows AC power state directly.

What I found is that whenever this happens, Windows actually reports:

AC → Battery → AC

for roughly 1–5 seconds.

I then checked the historical Windows Kernel-Power Event ID 105 logs. My System log goes back to March 2026, but the first occurrence of these short AC-loss events is August 12.

The interesting part is that KB5121003 was installed on my system late on August 11.

Since then I have recorded around 40 AC power transitions, most lasting only a few seconds. Examples:

07:41:55 → 07:42:02
13:12:35 → 13:12:36
17:17:50 → 17:17:52
02:17:32 → 02:17:37

and many more over the following days.

Windows Kernel-Power itself logs AcOnline=false, followed shortly by AcOnline=true, so this isn't only the battery icon/UI changing.

Another strange detail is that the physical charging LED on the laptop can remain on while this happens.

I have now temporarily uninstalled KB5121003 as a test.

Before rollback:

Windows 11 25H2 – Build 26200.9168

After rollback:

Windows 11 25H2 – Build 26200.8875

Windows Update is paused and I haven't changed anything else: same Intel driver, NVIDIA driver, BIOS, Hybrid Mode, Optimus settings, charger, etc.

I'm currently running a 50 ms AC-state monitor for the next 24–48 hours to see whether the AC_LOST events disappear after removing KB5121003.

Obviously this doesn't prove the update is responsible yet. It could still be Lenovo firmware/EC behavior or a hardware power issue. But the fact that the event history starts immediately after this update is suspicious enough that I'm testing it as the only changed variable.

Has anyone else on KB5121003, especially Lenovo Legion users, noticed random Kernel-Power 105 events, brief AC-to-battery transitions, or black screens that started around August 12?

I had to rebuild a windows installer on usb with my MacBook and now it’s running semi-proper but if I run that damn security update it bricks the whole system until I roll it back. Any suggestions?

A few months ago I checked for system updates on my Lenovo Legion and the Windows Update patch also included a BIOS firmware update.

After the update, every time that I booted the laptop an error of:

>

popped out and did not let me continue.

I tried every possible scenario on the internet, including guides from Microsoft and Lenovo themselves, and it did not work. One solution was to re-install Windows 11 again to solve this issue, which I wanted to avoid (yes, I am extremely lazy). However, none of the solutions worked.

Today I just had this idea that I did not try Claude Code to solve this issue. So I opened an elevated PowerShell instance and explained the situation. Took me 5 minutes to fully depict my concerns, 10 minutes Claude working its stuff, one reboot and it was fixed. Plus another 5 minutes to cleanup what Claude had done by continuing the same conversation.

Verifying everything was working perfectly, I told it to create a Markdown file so that if the issue occurs again we can use that to resolve it.

As this problem was a real headache for me, I am sharing the Markdown here.

Maybe this would help someone out. Cheers!

Secure Boot "Boot Manager Blocked by Current Security Policy" — Fix Notes

Machine

• [Your machine model]
• [BIOS/UEFI version]
• [BitLocker status on/off (you can verify this using Claude again)]

Symptom

After a Windows update, enabling Secure Boot in BIOS causes:

>

and the system won't boot.

Disabling Secure Boot lets it boot normally.

Root Cause

Part of the ongoing 2024–2026 Windows Secure Boot certificate migration (2011 certs expiring June 2026, replaced by "Windows UEFI CA 2023" certs).

A Windows update updates the Secure Boot DB/KEK on the firmware side, and the on-disk Boot Manager's signature stops validating against it.

Reinstalling Windows is not required and does not fix this — it's a firmware key-database issue, not a Windows install issue.

What Did NOT Work

• BIOS Secure Boot key reset (Security > Secure Boot > Clear Keys > Restore Factory Keys) — tried, did not resolve it.
• Firmware update — not applicable, already on latest Lenovo BIOS at time of issue.

What DID Work — Internal Secure Boot Recovery (No USB Needed)

Windows ships a signed repair tool at:

C:\Windows\Boot\EFI\SecureBootRecovery.efi

Normally Microsoft's docs have you put this on a USB stick renamed to bootx64.efi and boot from it.

Since no USB was available, the same trick was done using the internal EFI System Partition (ESP) instead — the ESP already had a stale:

\EFI\Boot\bootx64.efi

fallback file that was just a plain copy of the blocked boot manager, which is why the automatic fallback wasn't self-healing.

Steps

Run from a working Windows session, e.g. with Secure Boot temporarily off.

Find the ESP (should be Disk 0, ~260 MB "System" partition, no drive letter):

Get-Partition | Where-Object { $_.GptType -eq '{c12a7328-f81f-11d2-ba4b-00a0c93ec93b}' }

Mount it temporarily as Z::

Add-PartitionAccessPath -DiskNumber 0 -PartitionNumber 1 -AccessPath "Z:"

Back up the existing fallback file, then replace it with the recovery tool:

Copy-Item "Z:\EFI\Boot\bootx64.efi" "Z:\EFI\Boot\bootx64.efi.bak" -Force

Copy-Item "Z:\EFI\Microsoft\Boot\SecureBootRecovery.efi" "Z:\EFI\Boot\bootx64.efi" -Force

Unmount the ESP:

Remove-PartitionAccessPath -DiskNumber 0 -PartitionNumber 1 -AccessPath "Z:"

Reboot into BIOS (F2), Security > Secure Boot > Enabled, save & exit (F10).

Windows Boot Manager fails its policy check as before, but firmware automatically falls through to:

\EFI\Boot\bootx64.efi

which now runs the Secure Boot Recovery tool (blue Microsoft screen).

It repairs the Secure Boot key database and reboots automatically into normal Windows.

If no automatic fallback/blue screen appears and it just shows the same blocked error: use the one-time boot menu (tap F12 at power-on) and pick the generic "Internal Storage" / "UEFI OS" entry (not "Windows Boot Manager") to force it to use:

\EFI\Boot\bootx64.efi

Verify It Worked

Confirm-SecureBootUEFI

Should return True.

bcdedit /enum firmware

{bootmgr} should point to:

\EFI\Microsoft\Boot\bootmgfw.efi

Cleanup

Once confirmed working, restore the fallback file back to normal so it doesn't stay pointed at the recovery tool long-term:

Add-PartitionAccessPath -DiskNumber 0 -PartitionNumber 1 -AccessPath "Z:\"

Copy-Item "Z:\EFI\Boot\bootx64.efi.bak" "Z:\EFI\Boot\bootx64.efi" -Force

Remove-Item "Z:\EFI\Boot\bootx64.efi.bak" -Force

Remove-PartitionAccessPath -DiskNumber 0 -PartitionNumber 1 -AccessPath "Z:\"

I just got this (optional) driver update and wondering if i should install this and/or it safe? And what are the changes, not seeing any MSI update details online. I know last update was (1.0.0.15) a few months ago.

Hello i have tried a few solutions to try and fix the problem, i have run the system repair tool using the command prompt using DISM following all the prompts on the Microsoft learn website for the error code, it tells me the component store is repairable but at the end of the restore health prompt it tells me it can't find the repair content it gives me this error code 0x800f0915 and tried using the troubleshoot for windows updates and it tells me it failed to run the windows automated diagnostic tool, i have also downloaded the files for the update by itself and it installed them to the cache but couldn't update the security update i need, i have also uninstalled a older windows update and security update and ran a files check/repair on my main c disk drive but it still gives out the same error code each time I've tried. any help would be greatly appreciated

Title, it freezes on startup, sometimes before i can even write my password. After force restar it doesnt even start anymore. Was able to boot it once on safe mode after testing ram and gpu, no idea how i proc it, everything seemed fine, then i tried to normal boot and its back at the same behaviour. I reset the mboard, i flashback bios, ive tried multiple monitors and even the igpu on my ryzen 7600 and nothing fixes it...

Im trying to create a recovery usb atm but im not sure my pen has enough storage so im stuck, ive been troubleshootin all day and cant find a solution im losing my damm mind

bonjour, je rencontre un problème avec la mise à jour KB5121003 sous W11 depuis Windows update. Elle se télécharge mais bloque lors de l'installation et affiche un code erreur 0x80070002. j'ai essayé diverse soutions pour l'installer telle que l'installation manuelle ou vider le cache de Windows update mais rien n'y fait. avez-vous une solution ? je rpécise que j'ai W11 25h2 sur un pc non compatible à la base (juste pour le processeur qui est i5 7e génération)

Yesterday my laptop auto installed windows update KB5092427 and then security update KB5121003 and ever since then my laptop has been behaving erratically. It randomly becomes unresponsive, trackpad keyboard power button, nothing works and sometimes it even shuts down on it's own and as if by pure chance, decides whether to keep my opened apps open or close them with no fixed pattern.

Also a minor issue but it's also been getting the system time wrong on multiple occasions since yesterday and idk if it's related or not.

Idk if the update caused these issues, but the timing is just too weird to neglect.

My laptop is an Acer Aspire with AMD Ryzen 7730U processor. It has 16 GB RAM and 477 GB storage, out of which only 161 GB is occupied. Windows 11 25H2 version.

I've been using the laptop for an year atp and these issues have never happened, sure it did sometimes get overwhelmed and took a second or two to register my inputs (not very often) but never became completely unresponsive for over 15 mins straight, which was enough to send me into a panic. And the system time issue has literally never happened before.

If anyone else also had similar issues and knows how it can be fixed then plz let me know as this is my main and only device i use for all work and streaming.

I’m not sure what else to say about this. I tried going to the Windows support number only to meet an AI that talked in a circle for 30 minutes instead of actually helping me. I talked to one of my friends who is trained and such and basically got "Yeah, everything is fucked”

at the start of the morning I woke up to the laptop, despite having automatic updates or just generally updates even turned on to happen; it was auto-updating. I could not stop it from happening, and when I finally managed to get my device to turn back on, I literally could not do anything after I logged in for at-least five minutes. I couldn’t click on any of my apps, as well as not being able to even close out any apps that I have that auto-start. I can't click on the taskbar to open up task manager to try and figure out what is happening. It has progressively gotten worse to the point where I literally cannot even type in the login screen; I cannot even put in my password at all. I am stuck here, staring at a laptop that does not fucking work anymore, consistently getting Microsoft support that does not help or tells me to go to the website that also has not fucking helped me.

Before anyone suggested it, I had tried multiple times to boot into safe mode or security mode or whatever the fuck it’s called with the multiple methods I’ve been told and the ones I looked up, and it literally just won't.

https://preview.redd.it/umvtgxpxf2jh1.png?width=1024&format=png&auto=webp&s=80046df587b6c2967e74e6459e92efa8133abe87

I haven't been able to update my Surface pro 11 snapdragon X; I keep getting an error whenever I try. I've tried everything, but nothing works. Has this happened to anyone else?

Not sure if it's related to the Windows Update or a coincidence but I installed the latest windows update earlier today (2026-08 .NET Framework Security Update (KB5120708) + 2026-08 Security Update (KB5121003) (26200.9168)) and now things like chrome signed me out of everything, the icon doesn't load, tons of app icon's won't load, and things like Gaming Services files are 'missing' and I can't do things like screenshot/snip because I get an error. I ran /sfc scannow and other troubleshooting steps but nothing worked, so I'm going to reinstall Windows now. Thought I'd share this in case anyone is getting the same issues, I get there's probably a fix I can do but I'd rather reinstall Windows as it'd feel fresh anyways.

this all started when i tryed opening rust one morning and it gave me that error and i tried using AI to fix it i ended up restarting my pc and trying to iso it the AI said somthing about my version being beta and i looked it and it says my version expires yesterday or august 11 i tried iso it or like reseting and now it wont let me factory reset it and i isoed it or whatever from windows website and it wont let me do that saying somthing about booting or failed at boot. iv done alot and ai isnt working please help me im on windows 11 btw and im on version

https://preview.redd.it/3au7cchbg0jh1.png?width=453&format=png&auto=webp&s=99a2a295fb2aa84c84f3c08b69243f4a64221e80

Because of the discontinued updates, i would like to update my pc to windows 11

Currently im on windows 10, i just wanna ask if there is anything important i need to do before changing and generally if windows 11 is better

I have multiple games with and without mod files

Plus important documents

Should i save them externally before updating/can they get damaged if i update my pc?