PostgreSQL Connection Refused Fix

PostgreSQL Connection Refused: Troubleshooting Guide

Encountering a "connection refused" error when trying to connect to your PostgreSQL database can be frustrating. This error typically indicates that your client application cannot establish a connection with the PostgreSQL server. This article provides a step-by-step guide to diagnose and resolve this issue.

Common Causes and Solutions

Several factors can lead to a "connection refused" error. Here's a breakdown of the most common causes and how to address them:

1. PostgreSQL Server Not Running: This is the most frequent cause. Verify the PostgreSQL service is active. On Linux systems, use systemctl status postgresql. If it's stopped, start it with systemctl start postgresql. On Windows, check the Services application.
2. Incorrect Hostname or Port: Double-check the hostname and port number in your connection string. The default PostgreSQL port is 5432. A typo or incorrect configuration can prevent the connection. For example, ensure you're using 'localhost' or the server's IP address, and that the port is indeed '5432'.
3. Firewall Restrictions: Firewalls can block incoming connections to the PostgreSQL server. Ensure your firewall allows connections to port 5432. On Linux, use ufw allow 5432/tcp (if using UFW). On Windows, configure Windows Defender Firewall to allow inbound connections to the PostgreSQL executable (postgres.exe).
4. listen_addresses Configuration: The listen_addresses parameter in the postgresql.conf file controls which IP addresses the server listens on. By default, it might be set to localhost. To allow connections from other machines, change it to '*' (all interfaces) or a specific IP address. Remember to restart the PostgreSQL server after modifying this file. The postgresql.conf file is typically located in the /etc/postgresql/[version]/main/ directory on Linux, where [version] is your PostgreSQL version (e.g., 14).
5. pg_hba.conf Configuration: The pg_hba.conf file controls client authentication. Ensure there's an entry allowing connections from your client's IP address. A typical entry might look like this: host all all 192.168.1.0/24 md5. This line allows connections from the 192.168.1.0/24 network using MD5 password authentication. Restart PostgreSQL after making changes to pg_hba.conf.

Advanced Troubleshooting Tips

If the above steps don't resolve the issue, consider these advanced troubleshooting tips:

• Check PostgreSQL Logs: Examine the PostgreSQL server logs for error messages. These logs often provide valuable clues about the cause of the connection problem. The location of the logs is specified in the postgresql.conf file.
• Test with psql Locally: Try connecting to the database using the psql command-line tool on the server itself. This helps determine if the issue is with the server or the client configuration. For example: psql -U postgres -d postgres.
• Network Connectivity: Verify basic network connectivity between the client and server using tools like ping or traceroute.

By systematically checking these potential causes, you should be able to identify and resolve the "connection refused" error and successfully connect to your PostgreSQL database.