Public bug reported:

Fresh installation of Ubuntu 26.04, fully up-to-date.

As discussed here:
https://discourse.ubuntu.com/t/84315

and presenting this bug report as requested by @ogra (Oliver Grawert) here:
https://discourse.ubuntu.com/t/84315/6

---

SUMMARY

After installing Ubuntu 26.04, I checked that everything was working
(including being able to reboot).

Normally, I change Grub to show the menu on boot, as I always do on a
fresh installation. I didn't realise that Ubuntu 26.04 has completely
changed the booting and Grub mechanisms, so I used the same method as on
previous releases.

Apparently, the system (specifically update-grub) should have refused to
try to implement my change, but instead it broke the system without the
ability to restore it.

---

HOW TO REPLICATE

1. Create a file /etc/default/grub.d/grubmenu.cfg (the name isn't
important) with the following lines:

GRUB_TIMEOUT_STYLE=menu
GRUB_TIMEOUT=8

2. Run sudo update-grub

3. Reboot

---

RESULTS

• The Grub menu displays only one option, specifically "UEFI Firmware
Settings". As expected, this option takes you to the BIOS settings.

• If you interrupt the boot sequence with the Esc key, you get the new
26.04 Grub options. However, "Continue to run mode" takes you to the
previous step.

• There appears to be no way to restore the system to working order; I
couldn't figure it out. I tried running the restore option, but it
didn't work for me.

• I have retried this with reliably repeatable results.

---

SYSTEM

$ lsb_release --all
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 26.04 LTS
Release:        26.04
Codename:       resolute

• Fresh installation of Ubuntu 26.04, using TPM-backed full-disk
encryption with EFI and Secure Boot enabled. I haven't enabled Pro.

• This was done on VirtualBox (Host: Ubuntu 24.04), so it is in a VM. I
have not tried this on bare metal for obvious reasons.

ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: grub2-common 2.14-2ubuntu2
ProcVersionSignature: Ubuntu 7.0.0-22.22-generic 7.0.0
Uname: Linux 7.0.0-22-generic x86_64
ApportVersion: 2.34.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Sat Jun 20 14:50:54 2026
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: grub2
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: grub2 (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug resolute wayland-session

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https://bugs.launchpad.net/bugs/2157702

Title:
  Amending Grub on 26.04 breaks boot, with no way to fix it

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