Ubuntu 16.04 LTS – cron jobs stop running unexpectedly

📖 ~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

Scheduled automation misses execution windows, creating downstream operational gaps.

Environment & Reproduction

Common after permission changes, cron daemon restart issues, or malformed crontabs.

Root Cause Analysis

cron ignores entries with invalid format or cannot execute target scripts.

Quick Triage

Confirm cron service state and verify crontab syntax for affected users.

Step-by-Step Diagnosis

Review syslog cron entries and test command execution under cron environment.

Solution – Primary Fix

Repair crontab syntax, permissions, and environment assumptions for reliable runs.

Solution – Alternative Approaches

Migrate critical schedules to systemd timers for richer dependency control.

Verification & Acceptance Criteria

Scheduled jobs execute on time and produce expected outputs after remediation.

Rollback Plan

Revert cron file changes if new syntax introduces additional execution failures.

Prevention & Hardening

Add cron linting and heartbeat checks for high-value scheduled tasks.

Related Errors & Cross-Refs

Bad minute and permission denied in cron context are common indicators.

Related tutorial: View the step-by-step tutorial for Ubuntu 16.04 LTS.

View all Ubuntu 16.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Consult cron and systemd timer documentation for resilient task scheduling.