Unexpected Reboots Linked to Watchdog or Panic

📖 ~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

Host reboots without planned maintenance, often under load.

Environment & Reproduction

Kernel panic, hardware fault, watchdog timeout, or power instability.

Root Cause Analysis

Inspect last reboot reason with last -x and check for crash dumps in /var/crash.

Quick Triage

Disable nonessential risky modules and stabilize workload until root cause is identified.

Step-by-Step Diagnosis

Run dmesg -a, sysctl kern.panic_reboot_wait_time, and save current uptime/event data.

Solution – Primary Fix

Review /var/crash, /var/log/messages, and watchdog-related rc.conf flags.

Solution – Alternative Approaches

Enable dumpdev, collect core with kgdb workflow, test memory and storage health.

Verification & Acceptance Criteria

Monitor for sustained uptime through prior failure windows.

Rollback Plan

Keep firmware and kernel patches current with proactive hardware health checks.

Prevention & Hardening

Boot previous known-stable kernel and revert recent low-level changes.

Related Errors & Cross-Refs

Escalate immediately for repeated panics, suspected hardware defects, or data integrity risk.

Related tutorial: View the step-by-step tutorial for freebsd-15.

View all freebsd-15 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

last -x | head; dumpon -l; savecore -v /var/crash; sysctl -a | grep panic