Ubuntu 18.04 PostgreSQL Service Refuses Connections

📖 ~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

Applications cannot connect to PostgreSQL and data operations fail.

Environment & Reproduction

Seen after config edits, upgrades, or firewall policy changes.

Root Cause Analysis

Incorrect listen addresses, pg_hba rules, or service startup issues.

Quick Triage

Confirm database process is running and local socket accepts connections.

Step-by-Step Diagnosis

Inspect postgres logs, verify postgresql.conf and pg_hba.conf entries, test with psql.

Solution – Primary Fix

Correct listen and authentication settings, reload cluster, and open required firewall ports.

Solution – Alternative Approaches

Temporarily allow local trusted access for controlled emergency maintenance.

Verification & Acceptance Criteria

Application and manual psql tests connect successfully with expected roles.

Rollback Plan

Restore previous config backups and restart service if auth rules break.

Prevention & Hardening

Version control database configs and enforce staged configuration reviews.

Related Errors & Cross-Refs

Connection refused, no pg_hba.conf entry, could not connect to server.

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

PostgreSQL authentication and Ubuntu service management documentation.