Fix "Port Already in Use" / EADDRINUSE / localhost Refused

Last updated: March 16, 2025

Fix port conflicts when starting dev servers. Find and kill the blocking process, change ports for React/Next/Vite/Django/Flask/Docker, and prevent zombie processes.

Overview

Dev server won't start because the port is taken? This guide shows how to find and kill the blocking process, switch ports for any framework, and prevent it from happening again.

What this helps with

What to expect: Easy difficulty • usually about 2 minutes.

This is one of 28 Developer Tools & Programming fixes in the WindowsHelper library. The full step-by-step fix for this is in the WindowsHelper app.

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