Ubuntu 18.04 LTS – Common Problem 018 – 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

MySQL service fails to start, causing database downtime for dependent applications.

Environment & Reproduction

Ubuntu 18.04 with mysql-server package after config edits, disk pressure, or abrupt shutdown.

Root Cause Analysis

Invalid my.cnf settings, permission issues in /var/lib/mysql, or port/bind conflicts prevent startup.

Quick Triage

Run systemctl status mysql and inspect error log under /var/log/mysql/error.log.

Step-by-Step Diagnosis

Validate config with mysqld –verbose –help, check AppArmor profile interactions, and verify free space/inodes.

Solution – Primary Fix

Correct invalid directives, fix ownership to mysql:mysql, resolve port conflicts, then restart mysql service.

Solution – Alternative Approaches

Start with skip-networking for recovery tasks or restore from clean backup if data dictionary is corrupted.

Verification & Acceptance Criteria

mysql is active, local login succeeds, and application health checks pass.

Rollback Plan

Revert my.cnf changes and restore prior data snapshot if startup remains unstable.

Prevention & Hardening

Validate config changes in staging and maintain routine logical and physical backups.

Related Errors & Cross-Refs

InnoDB initialization errors, Can’t bind to address, and permission denied on datadir.

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

MySQL server docs, Ubuntu mysql package notes, and AppArmor MySQL profile references.