Ubuntu 14.04 LTS cron jobs stop running after timezone and DST changes

📖 ~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

Backup, cleanup, and report tasks run at wrong times or not at all.

Environment & Reproduction

Appears around daylight saving transitions or manual timezone adjustments.

Root Cause Analysis

Cron scheduling evaluates against inconsistent timezone settings or stale daemon context.

Quick Triage

Confirm system timezone, daemon status, and crontab syntax for affected jobs.

Step-by-Step Diagnosis

Review cron logs, compare expected schedule windows, and verify environment variables.

Solution – Primary Fix

Set consistent timezone policy, restart cron service, and normalize schedule expressions.

Solution – Alternative Approaches

Migrate critical tasks to UTC-based scheduling via orchestrated job runners.

Verification & Acceptance Criteria

Scheduled tasks execute at intended times over at least one full cycle.

Rollback Plan

Reapply previous timezone settings if dependent applications break under new policy.

Prevention & Hardening

Standardize on UTC and add job execution heartbeat monitoring.

Related Errors & Cross-Refs

CRON daemon restart warnings and missing expected job output logs.

Related tutorial: View the step-by-step tutorial for Ubuntu 14.04 LTS.

View all Ubuntu 14.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Cron behavior docs and timezone handling guidance for Linux servers.