π ~1 min read
Table of contents
Symptom & Impact
systemctl start returns dependency failed and critical daemon stays down, causing application outage.
Environment & Reproduction
After boot or package updates on RHEL 7, starting the unit repeatedly fails with Job for service failed due to dependency.
Root Cause Analysis
Unit ordering or Wants/Requires directives reference inactive targets or renamed services from legacy init scripts.
Quick Triage
Run systemctl status and journalctl -u target service to identify the first failed dependency in chain.
Step-by-Step Diagnosis
Use systemctl list-dependencies –reverse and inspect drop-ins under /etc/systemd/system for conflicting overrides.

Solution – Primary Fix
Correct unit dependency directives, run systemctl daemon-reload, then start dependency order explicitly and enable at boot.
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Solution – Alternative Approaches
For legacy components, temporarily use service command wrappers while migrating to native systemd unit files.
Verification & Acceptance Criteria
systemctl is-active returns active for all required units and reboot retains healthy startup order.
Rollback Plan
Restore previous unit file from backup, remove overrides, daemon-reload, and return to known working service chain.
Prevention & Hardening
Track unit file changes in version control and validate dependency graph in staging before production rollout.
Related Errors & Cross-Refs
Often paired with firewalld startup delays, missing mounts, or SELinux policy denials during early boot.
Related tutorial: View the step-by-step tutorial for rhel-7.
View all rhel-7 tutorials on the Tutorials Hub β
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Consult RHEL 7 systemd unit dependency documentation and troubleshooting patterns for failed jobs.
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