On Mon, Dec 06, 2021 at 10:56:29AM +0100, fran...@libero.it wrote: > Hello, > > unfortunately, nothing David suggested worked, so I finally set it on in the > bios Legacy (via F12) and then reinstalled Debian. > > Now if I turn on, Grub appears with Debian that starts (even if it takes a > while to boot) and if I want to use Windows, at boot, I have to click F12 and > select boot with UEFI and then Windows 10 starts. > > I tried to install os-prober on Debian, but it is already installed and doing > update-grub, but Windows is not shown (Probably because it is inserted in the > UEFI boot). > > Is there any way to fix this mess? > > Francesco
Hi Francesco, That _definitely_ won't work. If one OS is installed using UEFI, then both need to be. Can you delete the Debian you've installed / reboot and use rescue mode in expert mode. An expert install of Debian will allow you to specify where the boot files are. There is an option to install to a fallback location that should be found by any UEFI firmware. If you do that, it should work, and os-prober should also pick up the existing Windows installer. I think when I did this last time, I installed Debian first in UEFI mode and left space for Windows. Installing Windows thereafter it found the ESP partition and installed Windows boot files there. I think it might have made Windows default boot and ignored Debian. Rebooting Debian rescue mode and reinstalling grub and os-prober then found Windows and put the items into grub so that it is sorted out. All the very best, as ever, Andy C.
