I know there are approximately a million variants of this question, but please hear me out!

I have a Windows 10 Pro machine, upgraded from a Windows 7 Pro pre-install; both booted in UEFI mode. I can't find confirmation I can use Boot-Repair to fix my attempt to do a dual-boot installation of Ubuntu 16.04.3 in this situation.

I believe I made the common mistake of installing Ubuntu in Legacy (BIOS) mode during an attempt to install a dual-boot. Windows 10 boots as normal, and there does not appear to be any way to boot into Ubuntu.

I know the general recommendation is to use Boot-Repair to convert Ubuntu from Legacy to UEFI boot mode. But I've done a lot of research and there are contradicting answers about whether Boot-Repair is compatible with Windows 10 machines previously upgraded from Windows 7, as opposed to Windows 10 pre-installations. Also nearly all related advice involves a different mix of Ubuntu and Windows versions.


  1. Will Boot-Repair work with Windows 10 upgrades from Windows 7 pre-installations, both in UEFI mode?
  2. How can I verify that my issue is that I installed Ubuntu in Legacy, rather than something else?
  3. If I can't use Boot-Repair then what should I do?
  4. Would it be easier to uninstall Ubuntu and start the process all over again? How would I do that?
  5. Bonus: Does anyone have a link to very specific, detailed instructions for doing all this? Because all the information I've found is scattered across a lot of posts and websites and/or outdated.


  • Using a Lenovo T460. Upgraded to Windows 10 (and later Creator's Update) via Microsoft's upgrade program provided online.
  • Verified computer is currently booting in UEFI through Windows's System Information tool.
  • Fast Startup and Secure Boot were disabled.
  • Installed 16.04.3 via live-USB. Used customization option to create partition. It seemed to install as normal until I restarted the computer and tried to get into Ubuntu.
  • I think the installation didn't work because I can't find any option to boot to Ubuntu, whether through interrupting the normal boot process via function keys or using Advanced Startup (accessed through Windows PC settings).
  • I assume I installed in Legacy mode because I did not realize I was supposed to use UEFI until I started looking for reasons I couldn't boot to Ubuntu.
  • When I go into Disk Management (see photo), I see a random 1 MB partition (red) and two partitions (purple) that add up to the size of the partition I allocated for Ubuntu. I don't know what's up with that.
  • Just reinstall Ubuntu in UEFI mode. – Android Dev Sep 8 '17 at 18:41
  • How do I do the reinstall though? Don't I need to delete the existing installation (if there?) off the partition first? – JenJen Sep 8 '17 at 18:42
  • Well, you can delete all three of the Ubuntu partitions, and don't worry about nuking GRUB from the MBR, it's not doing any harm there. – Android Dev Sep 8 '17 at 18:44
  • 1
    FYI though - Windows 10 has a reputation for screwing up dual-boots after installing Windows updates – Android Dev Sep 8 '17 at 18:45
  • Is the 1 MB partition the third Ubuntu partition? Or is it something else? Full disclosure: when I first rebooted the computer only the 31 GB and 15 GB mystery partitions showed up. That 1 MB partition is a recent addition after another reboot. – JenJen Sep 8 '17 at 19:29

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