Ubuntu 18.04 LTS – Common Problem 021 – Diagnosis and Fix

📖 ~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

Required kernel module fails to load, disabling device or virtualization features.

Environment & Reproduction

Ubuntu 18.04 with DKMS modules after kernel updates and Secure Boot enabled on UEFI systems.

Root Cause Analysis

Module ABI mismatch, unsigned module rejection under Secure Boot, or missing kernel headers.

Quick Triage

Run modprobe , dmesg | tail, and mokutil –sb-state to confirm rejection reason.

Step-by-Step Diagnosis

Check dkms status, installed linux-headers package alignment, and module signature verification logs.

Solution – Primary Fix

Install matching headers, rebuild DKMS module, and sign/enroll key via MOK if Secure Boot enforces signatures.

Solution – Alternative Approaches

Temporarily disable Secure Boot in controlled lab scenarios while validating module packaging.

Verification & Acceptance Criteria

lsmod lists module, functionality is restored, and no signature or invalid format errors remain.

Rollback Plan

Boot previous kernel where module works and pin kernel until module compatibility is corrected.

Prevention & Hardening

Test DKMS rebuilds during patch cycles and maintain documented Secure Boot signing workflow.

Related Errors & Cross-Refs

modprobe: ERROR could not insert module, invalid module format, and Required key not available.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

DKMS docs, Ubuntu Secure Boot module signing guides, and modprobe manual.