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I've got a dual-booted system with Ubuntu 16.04LTS and Windows 10, the primary system being Ubuntu. I somehow managed to enable Secure Boot, which - I think - wiped Grub and now the system no longer boots anything. It just constantly goes straight to Dell's "System Repair" app.

After some recommendations, I tried using Boot Repair from the Ubuntu live USB (using the "Try Ubuntu without installing" option), but that did not seem to resolve it. I've been searching through these forums too, but I'm not seeing anything specific to my situation. I'm finding several "can only get to Windows" posts, but in my case - I can't get into anything.

How do I repair my Grub and get back to the dual-boot state?

Thanks very much in advance.


Update and solution

Thanks all. I ended up getting it fixed. I updated the "secure boot" setting to "off" shortly after things broke, but neglected to update to legacy BIOS. For some reason I thought that Grub2 worked with UEFI and the word "legacy" seemed like a shim for older stuff, so it didn't occur to me to try it.

Switching from UEFI to Legacy did the trick!

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  • 2
    Did you go back and disable secure boot? Aug 23, 2016 at 12:13
  • Enabling Secure Boot doesn't wipe anything, it just prevents stuff from booting. Disable it, Aug 23, 2016 at 12:37
  • Disable the secure boot.
    – Moksh
    Aug 23, 2016 at 12:57

3 Answers 3

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I don't think it "wiped grub", try accessing your (U)EFI and set the boot mode back to bios/legacy, that should solve it.

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  • That's actually funny. I run my installation of Ubuntu on (U)EFI. Does that mean I did something wrong?
    – James
    Aug 24, 2016 at 22:02
  • Not at all, I would even say it's better, because now with SecureBoot enabled only certified drivers will load. Regardless of the fact that you installed on UEFI or BIOS if you switch them after the installation they will not boot any longer.
    – Dan
    Aug 25, 2016 at 7:51
  • I wonder if one can somehow retain (UEFI) secure boot while having dual boot with Windows 10, without tinkering equivalent to setting your hair on fire.
    – matanox
    Aug 2, 2019 at 18:43
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Have you tried (re)installing grub via terminal?

sudo mount /dev/sda3 /mnt
sudo grub-install –boot-directory=/mnt/boot /dev/sda

I used sda(3) as an example.

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  • I was going to give this a shot if the above didn't work, but it did. Thank you for the suggestion!
    – zxbEPREF
    Aug 24, 2016 at 0:10
  • I'm happy to hear you can boot again. (:
    – Thomas
    Aug 24, 2016 at 0:16
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The solution was to switch from UEFI to Legacy and ensure that "Secure Boot" was set to off.

Thanks everyone!

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