# LOG: could not bind IPv4 address "0.0.0.0": Address already in use — Is another postmaster already running on port 5432?

**Code:** `port 5432 in use` · **Category:** PostgreSQL · **Seen on:** PostgreSQL

Another process (often a second PostgreSQL install or a container) already listens on 5432.

## Meaning

Homebrew + Postgres.app + Docker on the same machine commonly fight over 5432.

## Common causes

- Another PostgreSQL installation running
- Docker container publishing 5432
- Stale process

## Quick fix

1. Find the owner: lsof -i :5432
2. Stop the other instance or change the port

## Detailed fix by platform

### Linux

1. `sudo lsof -i :5432`

## How to diagnose

1. **Owner** — Which process holds 5432?
2. **Recent change** — Did it start after a deploy, upgrade, or configuration change? Compare with the last working version.

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Source: [WhatIsMyError](https://whatismyerror.com/errors/postgresql/could-not-bind-ipv4-port-5432)