On older systems that is Legacy / BIOS you should be able to DUAL boot if installed it legacy mode I'm a bit confused about this section of your post, you mention Debian, what version of Ubuntu are you trying to install or are you trying to install Debian? it has been my experience when installing Ubuntu on a system using UEFI, you need to install Ubuntu in UEFI, if this system is fairly new then it should be UEFI. To install Debian in UEFI mode, it might be difficult to reboot the machine into any BIOS-mode operating systems later. Is there anyway to load EFI in Legacy mode? If you wish to keep the option to boot an existing operating system, you should choose NOT to force UEFI installation here.Īs far as I can tell, the problem lies with windows booting in Legacy Mode and me loading Ubuntu in EFI. 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 continue to install Debian in UEFI mode, it might be difficult to reboot the machine into any BIOS-mode operating systems later. 'This machine'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'.

The problem is when I try to load Ubuntu from the USB, the only option to load Ubuntu is through EFI.Īnd when I try to install it, I get the message:

I've checked my boot options and windows is currently booting in Legacy Mode, with UEFI and secure boot options turned off. I'm working with a windows 10 laptop that has previously been installed with windows 7.

Universal usb installer ubuntu problem