Upgrade to 26.04.1 failed on reboot

Support and Help
,
1

Ubuntu Version

Ubuntu 26.04 LTS

Desktop Environment (if applicable)

GNOME

Problem Description

I just ran the upgrade from 24.04 to 26.04.1, and when my system did first reboot I got the following error message.
error: symbol ‘grub_memcpy’ not found
Entering rescue mode… ( then has the following prompt on next line)
grub rescue>

What commands am I supposed to enter to get my PC to boot so, I can fix this?
Also, how do I repair Grub?

2

Are you using UEFI or legacy BIOS boot?

3

UEFI, it’s a ROG motherboard.

4

There isn’t a command at the grub rescue prompt that will fix this, since the GRUB that loaded likely doesn’t match the modules the upgrade put in /boot/grub. I’d boot the 26.04 live USB, pick Try Ubuntu, and run sudo efibootmgr -v to check which disk and EFI file the ubuntu boot entry points to. Then find your root and EFI partitions with lsblk -f, mount root at /mnt and the EFI partition at /mnt/boot/efi, run for d in /dev /proc /sys /run; do sudo mount --rbind $d /mnt$d; done, and then sudo chroot /mnt. Inside the chroot run apt install --reinstall grub-efi-amd64 grub-efi-amd64-signed shim-signed, then grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=ubuntu and update-grub, and reboot.

Drafted with AI.

1 Like
5

I seem to have gotten lost trying to follow your instructions.

My Linux drive is sdb, a 2Tb SSD.

I’m thinking that a clean install on my 1Tb SSD might be the better idea, as my current install is easily 10+ years old since last time I did one. System was taking over two minutes to boot up so, will do that then copy my data across.

6

If it works it works. If you’d rather try the steps again or for anyone viewing the thread in the future:

  1. Boot from the Ubuntu 26.04 USB and choose Try Ubuntu.
  2. Open a Terminal (Ctrl+Alt+T).
  3. Find your partitions. Run:
   lsblk -f

Look for two partitions on your main drive:

  • The EFI partition: small (usually 100 to 500 MB), type vfat.
  • The Ubuntu partition: large, type ext4.

Note their names, for example nvme0n1p1 and nvme0n1p2, or sda1 and sda2.

  1. Mount them. Replace the names below with yours:
   sudo mount /dev/nvme0n1p2 /mnt
   sudo mount /dev/nvme0n1p1 /mnt/boot/efi
   for d in /dev /proc /sys /run; do sudo mount --rbind $d /mnt$d; done
   sudo chroot /mnt
  1. Reinstall GRUB. Run these one at a time:
   apt install --reinstall grub-efi-amd64 grub-efi-amd64-signed shim-signed
   grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=ubuntu
   update-grub
  1. Restart. Type exit, remove the USB stick, and run sudo reboot
7

Did you become lost because the instructions lacked detail?
Was there an error message?

Edit
More detail added by @et-ducky exactly when I posted my reply

8

Try (it removes the loops- slightly easier to digest)

lsblk -e 7
2 Likes
9

Thanks for your help. I did end up doing a clean install on a new drive, which has been nearly without issue. I had moved the disk image across a few different drives, and was at least 10 years of updates/upgrades without a clean install so, was probably overdue.

Except for Thunderbird, where I’ve lost all of the last two years saved emails. I’ve reached out for help on the Mozilla Thunderbird help forum, and just hope I get a response this time, as last time I posted an issue, absolute zero response.

Hopefully your fix can help someone else.

1 Like
10

Partly me having a bit of a problem working out commands from text, plus not being in the best of health. Clean install on a new partition has fixed it.

1 Like
11

Well done

Writing clear instructions is an art in itself.
Trying to take into account the level of knowledge required by the target audience often leads to:-

  • A long, turgid text
  • A brief explanation with a vital component missing

Anyway, its always good to read a successful outcome

2 Likes