Hayden

The “FATAL: password authentication failed for user” error is one of the most common PostgreSQL issues developers encounter. Whether you’re setting up a new database, working with Docker containers, or managing production systems, this error can stop your work in its tracks.

Don’t worry – I’ve dealt with this error countless times across different environments, and I’ll walk you through a systematic approach to diagnose and fix it quickly.

 

1. Quick Diagnosis Checklist

Before diving into complex solutions, let’s identify what’s causing your authentication failure:

Check these first:

  • ✅ Username and password are correct (no typos)
  • ✅ You’re connecting to the right host and port
  • ✅ PostgreSQL service is actually running
  • ✅ Your user account exists in the database

Get the full error message:

psql -h localhost -U postgres -d mydb
# Note: Save the complete error output for reference

Check PostgreSQL logs:

# Linux
sudo tail -f /var/log/postgresql/postgresql-*.log

# Docker
docker logs your_postgres_container

 

 

2. Most Common Causes and Solutions

Solution 1: Wrong Password or Forgotten Password

This is the #1 cause. Here’s how to reset it:

For local PostgreSQL installation:

# Switch to postgres user and connect
sudo -u postgres psql

# Reset the password
ALTER USER postgres WITH PASSWORD 'your_new_password';

For Docker containers:

# Connect to container
docker exec -it your_postgres_container psql -U postgres

# Reset password
ALTER USER postgres WITH PASSWORD 'your_new_password';

Solution 2: User Doesn’t Have a Password

If the cause of the error is the creation of a user or role without a password, log in to your PostgreSQL instance and set the password for the role.

-- Check if user exists but has no password
SELECT rolname, rolpassword FROM pg_authid WHERE rolname = 'your_username';

-- Set password for existing user
ALTER USER your_username WITH PASSWORD 'secure_password';

-- Create new user with password
CREATE USER new_user WITH PASSWORD 'secure_password';

Solution 3: pg_hba.conf Configuration Issues

PostgreSQL uses the pg_hba.conf file to configure client authentication. This file controls who can connect and how.

Step 1: Find your pg_hba.conf file:

# Find the file location
sudo -u postgres psql -c "SHOW hba_file;"

# Common locations:
# Linux: /etc/postgresql/[version]/main/pg_hba.conf
# Docker: /var/lib/postgresql/data/pg_hba.conf

Step 2: Edit the configuration:

# Edit the file (use your actual path)
sudo nano /etc/postgresql/14/main/pg_hba.conf

Step 3: Fix the authentication method:

Change this (problematic):

# TYPE  DATABASE        USER            ADDRESS                 METHOD
local   all             all                                     peer
host    all             all             127.0.0.1/32            ident

To this (working):

# TYPE  DATABASE        USER            ADDRESS                 METHOD
local   all             all                                     md5
host    all             all             127.0.0.1/32            md5
host    all             all             ::1/128                 md5

Step 4: Reload PostgreSQL:

# Linux
sudo systemctl reload postgresql

# Or
sudo -u postgres pg_ctl reload

# Docker
docker restart your_postgres_container

 

 

3. Docker-Specific Solutions

Docker environments have unique authentication challenges. Here’s how to handle them:

Fix Environment Variables

POSTGRES_HOST_AUTH_METHOD=scram-sha-256 POSTGRES_INITDB_ARGS=–auth-host=scram-sha-256

Complete Docker Compose setup:

version: '3.8'
services:
  postgres:
    image: postgres:15
    environment:
      POSTGRES_DB: myapp
      POSTGRES_USER: myuser  
      POSTGRES_PASSWORD: mypassword
      POSTGRES_HOST_AUTH_METHOD: md5
    ports:
      - "5432:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data

volumes:
  postgres_data:

Common Docker Troubleshooting

Problem: Port conflict with local PostgreSQL When you try to connect on docker postgres port 5432 you are connecting to your local machine postgres server

# Stop local PostgreSQL service
sudo systemctl stop postgresql

# Or use different port
docker run -p 5433:5432 postgres:15

Problem: Old volume data conflicts

# Remove old volumes and start fresh
docker-compose down -v
docker-compose up -d

Problem: Can’t connect from host machine

# Connect directly to container first
docker exec -it postgres_container psql -U postgres

# If this works, the issue is networking
# Check your connection string: postgresql://user:pass@localhost:5432/db

 

 

4. Authentication Method Guide

Understanding PostgreSQL’s authentication methods helps prevent future issues.

Recommended Methods by Use Case

Use Case Method Configuration
Local development md5 Safe and widely supported
Production scram-sha-256 Most secure, requires newer clients
Docker containers md5 or scram-sha-256 Specify in environment variables
Trusted network only trust ⚠️ No password required – use carefully

Upgrading to SCRAM-SHA-256 (More Secure)

The method scram-sha-256 performs SCRAM-SHA-256 authentication, as described in RFC 7677. It is a challenge-response scheme that prevents password sniffing on untrusted connections

Step-by-step upgrade:

-- 1. Enable SCRAM encryption for new passwords
ALTER SYSTEM SET password_encryption = 'scram-sha-256';
SELECT pg_reload_conf();

-- 2. Reset all user passwords (even if same password)
ALTER USER postgres WITH PASSWORD 'same_password';
ALTER USER your_user WITH PASSWORD 'their_password';

-- 3. Update pg_hba.conf
-- Change 'md5' to 'scram-sha-256' in your pg_hba.conf file

-- 4. Reload configuration
SELECT pg_reload_conf();

 

 

5. Step-by-Step Troubleshooting Process

Follow this systematic approach when the error occurs:

Step 1: Verify Basic Connection

# Test if PostgreSQL is running and accepting connections
pg_isready -h localhost -p 5432

# Try connecting with different users
psql -h localhost -U postgres
psql -h localhost -U your_username

Step 2: Check User Existence and Password

-- Connect as superuser and check user
sudo -u postgres psql

-- List all users
\du

-- Check specific user details
SELECT rolname, rolcanlogin, rolpassword FROM pg_authid WHERE rolname = 'your_user';

Step 3: Review Authentication Configuration

# Check current authentication settings
sudo -u postgres psql -c "SHOW hba_file;"
sudo cat /path/to/pg_hba.conf | grep -v "^#" | grep -v "^$"

Step 4: Test Different Authentication Methods

# Edit pg_hba.conf temporarily to use 'trust' method
# This allows connection without password for testing
# ⚠️ Remember to change back to secure method after testing

# Reload and test
sudo systemctl reload postgresql
psql -h localhost -U postgres

Step 5: Check Logs for Detailed Error Information

# Monitor logs while attempting connection
sudo tail -f /var/log/postgresql/postgresql-*.log

# Look for specific error patterns:
# - "no pg_hba.conf entry for host"
# - "password authentication failed"
# - "role does not exist"

 

 

The “FATAL: password authentication failed” error is frustrating, but it’s almost always one of a few common issues: wrong credentials, missing user passwords, or authentication method mismatches. By following this systematic approach – starting with the most common causes and working through the troubleshooting steps – you’ll resolve the issue quickly and understand how to prevent it in the future.

 

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