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windows 11 update disaster I now have EFI on one disk and windows on another

john ramsey 20 Reputation points
2026-01-22T09:43:40.1+00:00

My PC motherboard has 4 M.2 slots all occupied as I have extensive Steam libraries afte 15 16 years.

My System has operated perfecrtly since 2022 when i did my last full fresh instal and i have maintained the system properly. Not odd behaviour just the occasional glitches normally caused by games crashing etc and Nvidea updates.

The actual OS Windows 11 whilst less appealing than Windoiws 10 does at least allow me to do everything i need. It is purely a web gaming PC so no work no office needs etc.

4 days ago Win 11 updated even after I had specifically set the updates to wait 4 weeks in settings.

I had checked deliberately as i always do when I see a message saying update available.

So open settings I check that it is set to wait and then return to the desktop. Finished closing down apps that i had open and selected SHUTDOWN. I absolutely did not press update and shutdown or update and restart.

so MS in its wisdom after I had shut down rebooted and installed the update. I noticed this when i returned from the Bathroom to prepare for bed when i see the PC is on? So long story short I have since that time been trying to fix the dammed PC.

PC boot failure.

PC repair cannot fix

Recovery mode borked

Load restore point failed as disk is locked

every option tried and every time failed.

No worriess I have a full back up.

Backup does not work as message was abvout not same drive or hardare.

So last resort reinstal windows

Lucky I had the full creation media file and ISO on a USB drive.

it updated on the fly and when finished everything works but i now have to choose which drive to select. The issues are

My C drive is now on a different 2TB drive whilst my EFI partion is still on what was the original 1 TB drive

if either one is removed the system cannot boot. the original 1 TB C drive M.2 simply does not allow formatting or reinstallation it is essentially now useless to me but i have to leave it sitting there as if removed I am stuck in a loop of booting and media missing even though I instruct via bios to boot from the USB.

I did format another drive as I can redownload my games via steam but when I removed everything leaving only the newly formatted drive and the USB it starts the process then Microsoft is so kind to tell me refresh as windows caqnnot be installed on this drive ???????

Any help would be welcome as I am almost 70 and too dammed tired to go learn linux

Windows for home | Windows 11 | Windows update
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Answer accepted by question author

DaveM121 889.2K Reputation points Independent Advisor
2026-01-22T10:25:16.4233333+00:00

When you re-install Windows using a bootable USB, any drive that previously had a Windows installation must be disconnected, otherwise the installation will not create a new boot partition on the correct drive, this allows users to create a dual boot system.

You indicate you have tried to install Windows on another drive with just the USB and that drive connected, please try that again and when you see the error indicating Windows cannot be installed on that drive, please provide a photo of that window showing the target drive and partitions.

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  1. AI answer

    2026-01-22T09:43:56.6066667+00:00

    It sounds like you're experiencing a complex boot issue after a Windows 11 update that has left your system in a difficult state. Here are some steps you can take to try to resolve the situation:

    1. Check BIOS Settings: Ensure that your BIOS is set to boot from the correct drive. Sometimes, after updates or changes, the boot order can be altered.
    2. Repair the Boot Configuration: You can use the Windows installation media to access the recovery environment and attempt to repair the boot configuration. Here’s how:
      • Boot from the Windows installation USB.
      • Select "Repair your computer".
      • Choose "Troubleshoot" > "Advanced options" > "Command Prompt".
      • In the Command Prompt, run the following commands: 
             bootrec /fixmbr
     bootrec /fixboot
     bootrec /scanos
     bootrec /rebuildbcd
      • Restart your PC and see if it resolves the boot issue.
    3. Use Diskpart: If you have access to the Command Prompt via the recovery environment, you can use Diskpart to check the status of your drives and partitions. You can also try to assign a drive letter to the EFI partition if it doesn’t have one:
      • In Command Prompt, type diskpart and hit Enter.
      • Type list disk to see your drives.
      • Select your EFI partition (usually a small partition around 100-500MB) with select disk X (replace X with the disk number).
      • Type list partition to see partitions on that disk.
      • Select the EFI partition and assign a letter with assign letter=Z: (or any available letter).
      • Exit Diskpart and try to boot again.
    4. Reinstall Windows: If all else fails, you may need to perform a clean installation of Windows. Make sure to back up your data if you can access it. When reinstalling, ensure you select the correct drive for the installation. If you encounter issues with the installation media recognizing the drive, check that the drive is formatted correctly (GPT for UEFI systems).
    5. Check for Hardware Issues: Given the complexity of your situation, it may also be worth checking if there are any hardware issues, especially with the M.2 drives. You can use tools like CrystalDiskInfo to check the health of your drives.

    If you continue to have issues, consider seeking assistance from a professional technician who can provide hands-on help.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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  2. john ramsey 20 Reputation points
    2026-01-30T13:39:12.58+00:00

    Hi Dave apologies for such a late reply.

    I did as you suggested and used the delete function which allowed me to finally install the System anew.

    Sadly as a consequence all data passwords and login info to accounts that i have used for countless years were sent to the void.

    This evening only just gotten my email account fixed and regained access after many days of communication so finally able to reply.

    Just wanted to offer my thanks for your help as I was almost ready to throw the entire PC out the Window along with windows 11 as the update simply did a scorched earth on my system.

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  3. john ramsey 20 Reputation points
    2026-01-22T12:29:28.25+00:00

    Hi Dave thanks for the advice but i did try format but I dont think I tried to delete.

    I will need to take the PC apart again LOL

    No matter as i really want to keep the Boot drive as a 1TB and the rest as drives for games back up photos etc etc. Right now I have total of 3TB in use just to run windows.

    I shall let you know if I was successful tomorrow and thanks for the assistance

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