FreeBSD 15: freebsd-update install conflicts with custom kernel

📖 ~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

System updates abort or leave partial state, increasing risk of drift and boot inconsistency.

Environment & Reproduction

Occurs when GENERIC assumptions in update process conflict with locally compiled kernel artifacts.

Root Cause Analysis

Binary update workflow expects stock kernel paths and metadata not present in custom builds.

Quick Triage

Determine current kernel lineage, update stage, and whether merge conflicts affected critical files.

Step-by-Step Diagnosis

Audit update logs and kernel inventory to identify exact mismatch between expected and local state.

Solution – Primary Fix

Align kernel workflow with source-based process, then complete userland update safely.

Solution – Alternative Approaches

Temporarily boot GENERIC for update execution before reapplying tested custom kernel build.

Verification & Acceptance Criteria

Kernel and userland versions are coherent and reboot completes with expected modules loaded.

Rollback Plan

Reboot into prior boot environment and restore pre-update kernel artifacts from snapshot.

Prevention & Hardening

Document kernel update policy and test update path in staging before production rollout.

Related Errors & Cross-Refs

Often linked with ABI mismatch messages and third-party module load failures.

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

freebsd-update man page, FreeBSD Handbook update chapter, and kernel build docs.