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GRUB Reinstallation for Mint

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Source: ChatGPT data export · Conversation ID: 6a35d5f4-8128-83e8-a9a2-f7203616c216

Created: 2026-06-19T16:51:48-07:00 · Part 1 of 1

Darren2026-06-19T16:51:47-07:00

so on my test machine I'm installing linux mint, and it goes well be never actually writes the HD as bootable. I am now booted with usb stick into that OS, soooo? Select HD in interface and select make bootable somehow?

ChatGPT2026-06-19T16:51:48-07:00 · gpt-5-5-thinking

I’ll give you the safe “from the live USB” path: first identify whether the install is UEFI or legacy BIOS, then reinstall GRUB to the internal drive rather than just toggling a bootable flag.

ChatGPT2026-06-19T16:51:57-07:00 · gpt-5-5-thinking

No — don’t just select the HD and toggle “bootable.” That flag mostly matters for old BIOS/MBR installs. What you want is to reinstall GRUB to the internal drive and, if it is UEFI, make sure the EFI boot entry points to Mint.

Mint uses Ubuntu-style boot plumbing underneath, and the Linux Mint docs note that in EFI mode the boot entry may even appear as ubuntu, not linuxmint. citeturn795285view0 Ubuntu’s GRUB docs also emphasize: install GRUB to the disk, like /dev/sda, not a numbered partition like /dev/sda1. citeturn795285view1

Open a terminal from the live USB and do this:

lsblk -f

Find your installed Mint root partition, probably something like:

/dev/sda2   ext4   ...

And if UEFI, find the EFI partition, usually:

/dev/sda1   vfat   FAT32   ...

Check whether you booted the USB in UEFI mode:

[ -d /sys/firmware/efi ] && echo UEFI || echo BIOS

If it says UEFI

Replace /dev/sda2 with your Mint root partition, and /dev/sda1 with the EFI partition:

sudo mount /dev/sda2 /mnt
sudo mount /dev/sda1 /mnt/boot/efi

for i in /dev /dev/pts /proc /sys /run; do sudo mount --bind $i /mnt$i; done

sudo chroot /mnt

Now inside the installed system:

grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=ubuntu --recheck
update-grub
exit

Then unmount and reboot:

for i in /run /sys /proc /dev/pts /dev; do sudo umount /mnt$i; done
sudo umount /mnt/boot/efi
sudo umount /mnt
sudo reboot

Remove the USB when it tells you or when the screen goes black.

If it says BIOS / Legacy

Replace /dev/sda2 with the Mint root partition. Replace /dev/sda with the actual internal drive, no number at the end:

sudo mount /dev/sda2 /mnt

for i in /dev /dev/pts /proc /sys /run; do sudo mount --bind $i /mnt$i; done

sudo chroot /mnt
grub-install /dev/sda
update-grub
exit

for i in /run /sys /proc /dev/pts /dev; do sudo umount /mnt$i; done
sudo umount /mnt
sudo reboot

The most likely fix is the UEFI version. After reboot, also check BIOS/UEFI boot order and put the internal drive / ubuntu / Linux Mint entry above the USB drive.

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