📖 ~1 min read
Table of contents
Symptom & Impact
Systems reboot into grub rescue or missing menu entries, causing production outage risk.
Environment & Reproduction
Appears after kernel and grub package upgrades on UEFI or BIOS layouts with inconsistent boot config.
Root Cause Analysis
GRUB modules, bootloader target, or generated grub.cfg do not match active disk and partition metadata.
Quick Triage
Boot from previous kernel entry if available and capture /boot, EFI, and blkid state.
Step-by-Step Diagnosis
Validate mount points, UUID references, and grub-install target from a rescue chroot session.
Solution – Primary Fix
Reinstall grub packages, run grub-install to correct device, regenerate grub.cfg, and confirm initramfs images.
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Solution – Alternative Approaches
Restore from bootable snapshot or temporarily pin known-good kernel while validating storage topology changes.
Verification & Acceptance Criteria
Host boots cleanly without manual intervention and selected kernel matches expected Bullseye release.
Rollback Plan
Revert grub changes and boot previous kernel entry if new configuration introduces instability.
Prevention & Hardening
Keep rescue media ready, monitor /boot capacity, and test bootloader updates in staging first.
Related Errors & Cross-Refs
grub rescue>, unknown filesystem, and no such partition after update incidents.
Related tutorial: View the step-by-step tutorial for Debian 11.
View all Debian 11 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Debian GRUB wiki, initramfs-tools docs, and UEFI boot troubleshooting notes.
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