RHEL 9: Kernel Updates Fail Because /boot Is Full

📖 ~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

`dnf upgrade` fails during kernel transaction with no space left on device for /boot.

Environment & Reproduction

Run `df -h /boot` and `rpm -q kernel` to assess free space and installed kernel count.

Root Cause Analysis

Inspect transaction history with `dnf history` and identify incomplete kernel installs.

Quick Triage

Ensure bootloader tools and system maintenance units are healthy before cleanup.

Step-by-Step Diagnosis

Use `journalctl -b | grep -i kernel` and `journalctl -b | grep -i dnf` for transaction failures.

Solution – Primary Fix

Remove obsolete kernels with `dnf remove –oldinstallonly –setopt installonly_limit=2 kernel`.

Solution – Alternative Approaches

Firewall settings are unrelated, but maintain standard host policy during maintenance windows.

Verification & Acceptance Criteria

SELinux typically does not block kernel package operations on default policy.

Rollback Plan

Install latest kernel, reboot, and confirm target kernel with `uname -r`.

Prevention & Hardening

Set appropriate `installonly_limit` in dnf configuration for small boot partitions.

Related Errors & Cross-Refs

Keep at least one known-good previous kernel entry in GRUB for fallback.

Related tutorial: View the step-by-step tutorial for rhel-9.

View all rhel-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Review RHEL package lifecycle and kernel retention recommendations.