π ~1 min read
Table of contents
Symptom & Impact
Critical services remain inactive after boot, impacting application availability.
Environment & Reproduction
Common after package upgrades or configuration drift in unit overrides.
systemctl --failedRoot Cause Analysis
Broken dependencies, missing files, or invalid unit overrides prevent successful start.
Quick Triage
List failed units and inspect recent boot errors.
systemctl --failed
journalctl -p err -bStep-by-Step Diagnosis
Check each failing unit status and dependency chain details.
systemctl status
systemctl list-dependencies --reverse
Solution – Primary Fix
Correct unit configuration, reload daemon, and restart affected services.
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sudo systemctl daemon-reload
sudo systemctl restart
sudo systemctl enable 
Solution – Alternative Approaches
Mask non-essential failing units to restore core service health quickly.
sudo systemctl mask Verification & Acceptance Criteria
No failed units remain and required service endpoints respond correctly.
systemctl --failed
systemctl is-active Rollback Plan
Revert drop-in overrides to prior known-good definitions and reload systemd.
Prevention & Hardening
Validate unit files in CI and monitor failed unit count after every deployment.
Related Errors & Cross-Refs
Can be coupled with mount failures, network-online target delays, and permission issues.
Related tutorial: View the step-by-step tutorial for Ubuntu 26.04 LTS.
View all Ubuntu 26.04 LTS tutorials on the Tutorials Hub β
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Ubuntu systemd unit management and troubleshooting documentation.
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