π ~1 min read
Table of contents
Symptom & Impact
System boots unexpectedly to one entry or bypasses expected boot menu options.
Environment & Reproduction
Typically occurs after package updates or changing default boot parameters.
grep -E '^GRUB_' /etc/default/grub
ls /boot/grub
sudo efibootmgr -v
Root Cause Analysis
GRUB config generation or EFI entry state became inconsistent.
Quick Triage
Confirm boot mode and existing EFI entries.
[ -d /sys/firmware/efi ] && echo UEFI || echo BIOS
sudo efibootmgr -v
sudo grub-mkconfig -o /boot/grub/grub.cfg
Step-by-Step Diagnosis
Inspect grub defaults and generated menu entries.
sudo cat /etc/default/grub
grep -n 'menuentry' /boot/grub/grub.cfg | head -n 20
sudo journalctl -b -0 | grep -i grub

Solution – Primary Fix
Reinstall/update GRUB and regenerate config.
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sudo grub-install
sudo update-grub
sudo efibootmgr -v

Solution – Alternative Approaches
Set explicit timeout and hidden menu options in grub defaults.
sudoedit /etc/default/grub
sudo update-grub
Verification & Acceptance Criteria
GRUB menu appears and expected entries are selectable.
grep -E '^GRUB_TIMEOUT|^GRUB_TIMEOUT_STYLE' /etc/default/grub
grep -n 'menuentry' /boot/grub/grub.cfg | head -n 20
Rollback Plan
Restore previous /etc/default/grub and regenerate.
sudo cp /etc/default/grub.bak /etc/default/grub
sudo update-grub
Prevention & Hardening
Track bootloader changes and keep rescue media available.
sudo apt-mark showmanual | grep grub
sudo efibootmgr -v
Related Errors & Cross-Refs
Can overlap with initramfs corruption and wrong EFI boot order.
Related tutorial: View the step-by-step tutorial for Ubuntu 24.04 LTS.
View all Ubuntu 24.04 LTS tutorials on the Tutorials Hub β
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Ubuntu GRUB and UEFI troubleshooting documentation.
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