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I had an installation of Ubuntu since > 3 years working well in a dual-boot setting with Windows 10. 90% of the times I use Ubuntu only, but today I booted into Windows to play a game and it took me for a ride of about 3 hours updating the OS.

Post that update, I realised whenever system was booting, it was directly going to UEFI file located at /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi.

After spending some 8+ hours trying to bring GRUB back from the grip of Windows, I replaced the path

/boot/efi/EFI/Microsoft/Boot/bootmgfw.efi

with file from

/boot/efi/EFI/ubuntu/grubx64.ef

I did take proper backup. The above setting did work, and now Grub is back from almost dead.

I am very curious to know more about how this thing happens, and Windows acquires a lock on which file the firmware will look up to.

I had secure boot disabled since few years. I had tried tools like EasyUEFI and efibootmgr, but on every reboot, the control was going straight to Windows.

This may be naive question, but can anyone please shed light on how UEFI lock happens and what can we do to prevent this from happening?

P.S: As of now, I have disabled Windows Update services to get rid of this trouble.

harkirat1892
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1 Answers1

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Although this problem affects Ubuntu if it is installed alongside Windows, it is caused by Windows, not Ubuntu, and there is no way to prevent Windows updates from overwriting the grub bootloader except by accepting the onerous consequences of disabling Windows Updates.

How to repair grub

karel
  • 114,770