Ubuntu 16.04 Cron Jobs Not Running from /etc/cron.d

📖 ~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

Expected automation tasks do not execute, causing backup, report, or maintenance delays.

Environment & Reproduction

Usually occurs when /etc/cron.d files have wrong permissions, format, or missing user field.

Root Cause Analysis

Cron daemon ignores malformed entries or non-compliant file metadata in cron.d directory.

Quick Triage

Confirm cron service status, check job file permissions, and review syslog execution records.

Step-by-Step Diagnosis

Validate cron syntax, environment assumptions, and executable path usage in scheduled commands.

Solution – Primary Fix

Correct cron.d file format and permissions, reload cron service, and test with traceable output.

Solution – Alternative Approaches

Use user crontab or migrate recurring tasks to systemd timers for better observability.

Verification & Acceptance Criteria

Jobs execute on schedule and expected outputs or logs appear reliably.

Rollback Plan

Restore previous cron definitions if updated schedule breaks dependent workflows.

Prevention & Hardening

Lint cron entries in CI and include explicit environment variables in job definitions.

Related Errors & Cross-Refs

Related to script permission denied and missing PATH command failures.

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

cron and crontab manual references plus Ubuntu scheduled task best practices.