Ubuntu 18.04 LTS – time sync unstable due to chrony and systemd-timesyncd conflict – 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

Clock drift and periodic sync loss affect auth, logs, and scheduling.

Environment & Reproduction

Ubuntu 20.04 with both chrony and systemd-timesyncd enabled.

Root Cause Analysis

Multiple daemons competing for time control lead to unstable sync state.

Quick Triage

Check active NTP services and source selection across tooling outputs.

Step-by-Step Diagnosis

Determine which daemon should own time sync per environment policy.

Solution – Primary Fix

Disable one daemon, keep a single authority, and verify stable synchronization.

Solution – Alternative Approaches

Use chrony for advanced drift control on virtualized or edge nodes.

Verification & Acceptance Criteria

Offset remains within tolerance and synchronized state persists.

Rollback Plan

Re-enable prior daemon and restore previous config set if needed.

Prevention & Hardening

Standardize NTP daemon choice in image templates and compliance checks.

Related Errors & Cross-Refs

Apt date errors and certificate validation failures can appear during drift.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

chrony and systemd-timesyncd operational guidance for Ubuntu.