Debian 13 systemd Timer or Cron Job Not Running

📖 ~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

Backups, maintenance scripts, or reports do not execute on schedule, risking data and operational compliance.

Environment & Reproduction

Seen when migrating from cron to systemd timers or when environment assumptions differ between interactive and scheduled runs.

Root Cause Analysis

Invalid timer/calendar syntax, missing executable permissions, or wrong PATH causes silent scheduling failures.

Quick Triage

Check last run timestamps and unit states before rewriting jobs that may only need environment fixes.

Step-by-Step Diagnosis

Use systemctl list-timers and journalctl for unit logs, then test command invocation with the same user context.

Solution – Primary Fix

Correct timer schedule and unit ExecStart path, reload daemon, and enable persistent timer behavior if required.

Solution – Alternative Approaches

Use cron for simple periodic tasks or orchestrator-based schedules for distributed job reliability.

Verification & Acceptance Criteria

Task runs at expected intervals and produces expected outputs with no schedule drift or permission errors.

Rollback Plan

Re-enable previous scheduler mechanism if new timer implementation fails service-level requirements.

Prevention & Hardening

Add health checks for schedule recency and monitor timer failures through centralized alerting.

Related Errors & Cross-Refs

Related to clock drift, missing executable bits, and environment variable assumptions in scripts.

Related tutorial: View the step-by-step tutorial for Debian 13.

View all Debian 13 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

systemd.timer docs, cron manuals, and Debian automation reliability recommendations.