Kernel Module Fails to Load After Update

📖 ~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

kldload returns Exec format error or unsupported version messages.

Environment & Reproduction

Out-of-tree module built for older kernel, missing dependencies, or wrong path.

Root Cause Analysis

Compare uname -K with module build metadata and run kldstat.

Quick Triage

Rebuild or reinstall module package matching current kernel release.

Step-by-Step Diagnosis

Run kldload and kldstat -v to inspect load attempts and dependencies.

Solution – Primary Fix

Inspect /boot/loader.conf and dmesg for module ABI mismatch details.

Solution – Alternative Approaches

Update package sources, reinstall module, and remove stale module files from old paths.

Verification & Acceptance Criteria

Confirm module loads at boot and target functionality returns.

Rollback Plan

Rebuild external modules after kernel updates and before production reboot.

Prevention & Hardening

Boot previous kernel or package set while preparing compatible module build.

Related Errors & Cross-Refs

Escalate for persistent panics or driver regressions in current release branch.

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

uname -a; kldstat; kldload ; dmesg | tail -n 100