📖 ~1 min read
Table of contents
Symptom & Impact
GRUB cannot regenerate config, raising risk of non-bootable system after next reboot.
Environment & Reproduction
Appears after partition resizing, UUID changes, or migration to new disk device naming.
Root Cause Analysis
Bootloader references stale device paths or UUIDs no longer matching current disk layout.
Quick Triage
Confirm active root and boot partition identifiers and compare with fstab and GRUB configs.
Step-by-Step Diagnosis
Inspect grub.cfg generation warnings and mount state for /boot and EFI paths.
Solution – Primary Fix
Correct UUID references, reinstall GRUB to target disk, and regenerate configuration.
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Solution – Alternative Approaches
Use live media chroot recovery if primary system cannot safely update bootloader.
Verification & Acceptance Criteria
GRUB updates without errors and reboot reaches expected OS entry successfully.
Rollback Plan
Restore previous partition map snapshot and bootloader artifacts from rescue backup.
Prevention & Hardening
Document disk changes, validate UUID mapping, and test reboot in maintenance windows.
Related Errors & Cross-Refs
grub-probe: cannot find a GRUB drive, unknown filesystem, and rescue prompt boot.
Related tutorial: View the step-by-step tutorial for Ubuntu 16.04 LTS.
View all Ubuntu 16.04 LTS tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
GRUB recovery best practices for Ubuntu 16.04 legacy infrastructures.
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