Systemd unit fails with dependency errors

📖 ~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

Critical service remains inactive because prerequisite units fail or are ordered incorrectly.

Environment & Reproduction

RHEL 7 custom unit files under /etc/systemd/system with recent manual edits.

Root Cause Analysis

Misconfigured After/Requires settings or missing target dependencies in unit definition.

Quick Triage

Run systemctl status and systemctl list-dependencies to locate failing parent.

Step-by-Step Diagnosis

Use journalctl -u -b and systemd-analyze verify to find syntax and ordering problems.

Solution – Primary Fix

Adjust unit dependencies, run systemctl daemon-reload, and restart units in proper sequence.

Solution – Alternative Approaches

Temporarily add ExecStartPre checks or legacy service wrapper until full refactor is complete.

Verification & Acceptance Criteria

Unit starts at boot and shows active (running) with all required dependencies satisfied.

Rollback Plan

Restore prior unit file from backup and daemon-reload to return original behavior.

Prevention & Hardening

Version-control unit files and run validation before promotion to production.

Related Errors & Cross-Refs

Dependency failed, Unit entered failed state, Failed to start due to ordering cycle.

Related tutorial: View the step-by-step tutorial for rhel-7.

View all rhel-7 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

systemd.unit man page, systemd-analyze docs, RHEL 7 service management guide.