psql: error: connection to server at "localhost" (127.0.0.1), port 5432 failed: Connection refused — how to fix

psql: error: connection to server at "localhost" (127.0.0.1), port 5432 failed: Connection refused
        Is the server running on that host and accepting TCP/IP connections?

Quick fix: Start the server: sudo systemctl start postgresql and check sudo systemctl status postgresql. Then verify the port with sudo ss -ltnp | grep 5432.

What it means

The TCP connection was actively refused: nothing is listening at that address and port. Authentication hasn't even started.

Step 1: is PostgreSQL running?

sudo systemctl status postgresql
sudo systemctl start postgresql

On Debian/Ubuntu each cluster has its own unit: pg_lsclusters shows clusters, ports and status. Start one with sudo pg_ctlcluster 16 main start.

macOS Homebrew: brew services start postgresql@16.

If it won't start, read the log: sudo journalctl -u postgresql -n 50 or /var/log/postgresql/.

Step 2: which port and address?

sudo ss -ltnp | grep postgres

A second installed version often takes port 5433. Connect with -p 5433 or change port in postgresql.conf.

Step 3: connecting from another machine or container

By default PostgreSQL listens only on localhost. In postgresql.conf:

listen_addresses = '*'

and allow the client network in pg_hba.conf:

host  all  all  10.0.0.0/24  scram-sha-256

Restart PostgreSQL, and open port 5432 in the firewall only for trusted networks.

Docker

• Publish the port: docker run -p 5432:5432 postgres.
• From another container, localhost means that container itself. Use the service name as the host (db, as defined in compose.yaml).
• depends_on doesn't wait for PostgreSQL to be ready. Add a healthcheck with pg_isready and use condition: service_healthy, or retry in your app.

Unix socket version of this error

connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: No such file or directory means the same thing over the socket: the server isn't running, or it uses another port (the port number is part of the socket name).

Last updated 2026-10-27.