PostgreSQL Connection Refused: Server Not Accepting Connections

# PostgreSQL Connection Refused: Server Not Accepting Connections

You're trying to connect to your PostgreSQL database, but instead of a prompt, you get this frustrating error:

psql: could not connect to server: Connection refused
	Is the server running on host "localhost" (127.0.0.1) and accepting
	TCP/IP connections on port 5432?

This error means the PostgreSQL server either isn't running, isn't listening on the expected address, or a firewall is blocking the connection. Let's diagnose and fix this systematically.

Diagnosing the Problem

Step 1: Check if PostgreSQL is Running

First, verify the PostgreSQL service status:

On Linux (systemd): ``bash sudo systemctl status postgresql

On Linux (older systems): ``bash sudo service postgresql status

On macOS (Homebrew): ``bash brew services list | grep postgresql

On Windows: ``cmd sc query postgresql-x64-16

If the service isn't running, start it:

sudo systemctl start postgresql

Step 2: Check the Listening Address and Port

PostgreSQL might be running but not listening on the address you're connecting to. Check the actual listening ports:

```bash # Linux/macOS sudo ss -tlnp | grep postgres # or sudo netstat -tlnp | grep 5432

# Check PostgreSQL's view sudo -u postgres psql -c "SHOW port;" sudo -u postgres psql -c "SHOW listen_addresses;" ```

The listen_addresses setting controls which IP addresses PostgreSQL accepts connections on:

• 'localhost' - Only local connections via 127.0.0.1
• '*' - All interfaces (requires listen_addresses = '*')
• Specific IP - Only that IP address

Step 3: Verify the Port in Configuration

Check the PostgreSQL configuration files:

```bash # Find the config file location sudo -u postgres psql -c "SHOW config_file;"

# View relevant settings sudo -u postgres psql -c "SHOW port;" ```

Common config file locations: - /etc/postgresql/16/main/postgresql.conf (Debian/Ubuntu) - /var/lib/pgsql/data/postgresql.conf (RHEL/CentOS) - /usr/local/var/postgres/postgresql.conf (macOS Homebrew)

Common Causes and Solutions

Cause 1: Server Not Running

Symptoms: No PostgreSQL process found, systemctl shows inactive/dead.

Solution: ``bash sudo systemctl start postgresql sudo systemctl enable postgresql # Auto-start on boot

Cause 2: Wrong Port Number

Symptoms: PostgreSQL running on non-default port (5433 instead of 5432).

Solution: Either connect with the correct port or change the configuration:

```bash # Connect with correct port psql -h localhost -p 5433 -U postgres

# Or change port in postgresql.conf port = 5432 ```

After changing configuration, restart:

sudo systemctl restart postgresql

Cause 3: Not Listening on Expected Address

Symptoms: listen_addresses is set to 'localhost' but you're connecting from another host.

Solution: Edit postgresql.conf:

listen_addresses = '*'  # Listen on all interfaces
# or
listen_addresses = '192.168.1.100'  # Specific IP

Then restart and update pg_hba.conf to allow remote connections:

# pg_hba.conf
host    all    all    192.168.1.0/24    scram-sha-256

Cause 4: Firewall Blocking Connection

Symptoms: PostgreSQL running and listening, but connections time out or get refused.

Solution: Check firewall rules:

Using firewalld (RHEL/CentOS): ``bash sudo firewall-cmd --list-all sudo firewall-cmd --add-service=postgresql --permanent sudo firewall-cmd --reload

Using ufw (Ubuntu): ``bash sudo ufw status sudo ufw allow 5432/tcp

Using iptables: ``bash sudo iptables -L -n | grep 5432 sudo iptables -A INPUT -p tcp --dport 5432 -j ACCEPT

Cause 5: Unix Socket vs TCP Connection

Symptoms: Connection works with psql -U postgres but fails with psql -h localhost -U postgres.

Diagnosis: ``bash # Check unix socket directory sudo -u postgres psql -c "SHOW unix_socket_directories;"

Solution: If using TCP explicitly, ensure listen_addresses includes localhost:

listen_addresses = 'localhost'

Verification Steps

After making changes, verify everything works:

```bash # Test local connection via Unix socket sudo -u postgres psql -c "SELECT version();"

# Test TCP connection psql -h localhost -p 5432 -U postgres -c "SELECT version();"

# Test from remote host psql -h 192.168.1.100 -p 5432 -U postgres -c "SELECT version();" ```

Check the PostgreSQL logs for any remaining issues:

```bash # Find log location sudo -u postgres psql -c "SHOW log_directory;"

# Common log locations tail -f /var/log/postgresql/postgresql-16-main.log tail -f /var/lib/pgsql/data/log/postgresql-*.log ```

Quick Reference

Related Errors

• "No such file or directory" - Unix socket file missing; check unix_socket_directories
• "Connection timed out" - Firewall blocking; check iptables/firewalld
• "FATAL: no pg_hba.conf entry" - Authentication config; see our pg_hba.conf guide