I'm on a fresh install of Elementary OS Loki. Right after the install screen about installing third-party and background updates, I have this pop-up:

Force UEFI installation?

This machines's firmware has started the installer in UEFI mode but it looks like there may be existing operating systems already installed using "BIOS compatibility mode". If you continue to install Debian in UEFI mode, it might be difficult to reboot the machine into any BIOS-mode operating systems later.

If you wish to install in UEFI mode and don't care about keeping the ability to boot one of the existing systems, you have the option to force that here. If you wish to keep the option to boot an existing operating system, you should choose NOT to force UEFI installation here.

In my case, the installed drives are blank, so I don't know why this message is being thrown, but is it smart to default new installs into UEFI mode? (Thus the only reason for desiring the old BIOS method would be compatibility with older, UEFI-incompatible operating systems?) Does this affect future installs of modern operating systems on this computer? Just wanted to confirm as I imagine many others will have the same questions.

1 Answer 1


I had this problem last night in my laptop and even tho I could solve it I don't have a technical explanation for you.

If you force install in UEFI mode it won't boot. As simple as that. I was looking for the reason behind this but all I could find was related to dual boot with Windows.

What I did was to force the installation (just click continue) and then get into my BIOS config and turn Legacy Mode on. After that your OS will boot without issues. If you don't turn Legacy Mode on the BIOS will throw a message at you saying that it couldn't find an OS.

  • "If you force install in UEFI mode it won't boot." Do you mean won't dual boot Windows? I force installed in UEFI and the install went fine
    – wolf
    Sep 16, 2016 at 4:00
  • I meant that it wouldn't boot elementary. In my case it didn't and I had to use Legacy Mode. Sep 16, 2016 at 13:24

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