CentOS Stream 9 – Common Problem 124 – Diagnosis and Fix

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

After kernel update, the system still boots the older kernel.

Environment & Reproduction

grubby –default-kernel points to a stale BLS entry.

Root Cause Analysis

BootLoaderSpec drop-ins under /boot/loader/entries/ are out of order.

Quick Triage

grubby –default-kernel and ls /boot/loader/entries/.

Step-by-Step Diagnosis

rpm -q kernel and grub2-editenv list compared to expected.

Solution – Primary Fix

grubby –set-default /boot/vmlinuz-; reboot.

Solution – Alternative Approaches

Regenerate BLS entries: kernel-install add or grub2-mkconfig as fallback.

Verification & Acceptance Criteria

uname -r matches the latest installed kernel after reboot.

Rollback Plan

grubby –set-default /boot/vmlinuz-.

Prevention & Hardening

Add kernel upgrade verification to post-patch automation.

Related Errors & Cross-Refs

Related: GRUB UEFI vs BIOS path and shim updates.

Related tutorial: View the step-by-step tutorial for centos-stream-9.

View all centos-stream-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Red Hat ‘Managing kernel modules’ and grubby(8).