🟠 High   ⏱ 5–30 min  Last verified: 20 May 2026
Affected versions: Ubuntu 24.04 LTS

πŸ“– ~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

TLS validation fails and apt repositories report certificate errors.

Environment & Reproduction

Common on VMs without proper NTP sync.

date -u
timedatectl status
sudo apt update

Root Cause Analysis

Clock drift exceeds certificate validity tolerance.

Quick Triage

Check NTP service state and RTC alignment.

timedatectl show-timesync --all
systemctl status systemd-timesyncd
hwclock --show

Step-by-Step Diagnosis

Review synchronization status and recent time adjustment logs.

timedatectl status
sudo journalctl -u systemd-timesyncd -n 100
chronyc tracking
Illustrative mockup for ubuntu-24-04-lts β€” terminal_or_shell
Time sync diagnostics with timedatectl β€” Illustrative mockup β€” Progressive Robot

Solution – Primary Fix

Enable NTP sync and force immediate resynchronization.

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sudo timedatectl set-ntp true
sudo systemctl restart systemd-timesyncd
timedatectl status
Illustrative mockup for ubuntu-24-04-lts β€” logs_or_journal
NTP sync logs after correction β€” Illustrative mockup β€” Progressive Robot

Solution – Alternative Approaches

Use chrony for stricter synchronization control.

sudo apt install -y chrony
sudo systemctl enable --now chrony
chronyc sources

Verification & Acceptance Criteria

Clock remains synchronized and TLS operations succeed.

timedatectl status
curl -I https://security.ubuntu.com
sudo apt update

Rollback Plan

Revert to previous NTP client if chrony integration fails.

sudo systemctl disable --now chrony
sudo systemctl enable --now systemd-timesyncd

Prevention & Hardening

Monitor drift and alert on NTP synchronization failures.

timedatectl show-timesync --all
systemctl is-active systemd-timesyncd

Often linked to hypervisor time sync conflicts.

Related tutorial: View the step-by-step tutorial for Ubuntu 24.04 LTS.

View all Ubuntu 24.04 LTS tutorials on the Tutorials Hub β†’

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Ubuntu time synchronization and NTP documentation.

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