Ubuntu 26.04 LTS – Swap re-enabled unexpectedly and breaks kubelet policy – Fix & Prevention

📖 ~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

Kubelet fails startup with swap enabled errors, making node unusable.

Environment & Reproduction

Can happen after cloud-init, fstab edits, or image rehydration.

swapon --show
sudo systemctl status kubelet
cat /etc/fstab

Root Cause Analysis

Swap devices become active at boot while cluster policy requires swap disabled.

Quick Triage

Confirm active swap and kubelet error messages.

swapon --show
sudo journalctl -u kubelet -n 80
free -h

Step-by-Step Diagnosis

Locate swap activation source in fstab or cloud-init.

grep -E 'swap' /etc/fstab
grep -R swap /etc/cloud -n
lsblk -f

Solution – Primary Fix

Disable active swap and remove persistent swap entries.

sudo swapoff -a
sudo sed -i.bak '/sswaps/s/^/#/' /etc/fstab
sudo systemctl restart kubelet

Solution – Alternative Approaches

If swap must stay, configure workload policies outside strict kubelet defaults.

sudo kubelet --help | grep -i swap

Verification & Acceptance Criteria

No active swap remains and kubelet node status is healthy.

swapon --show
kubectl get nodes
sudo systemctl is-active kubelet

Rollback Plan

Restore fstab backup and reactivate swap if non-Kubernetes workload needs it.

sudo cp /etc/fstab.bak /etc/fstab
sudo swapon -a

Prevention & Hardening

Enforce swap policy in image build and boot validation checks.

grep -E 'swap' /etc/fstab
systemctl is-enabled kubelet

Related Errors & Cross-Refs

Related to cgroup mismatch, kubeadm preflight failures, and OOM behavior changes.

Related tutorial: View the step-by-step tutorial for Ubuntu 26.04 LTS.

View all Ubuntu 26.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Ubuntu Kubernetes node prep guidance and swap configuration notes.