React Native

Localhost 8081 Blocked?

Port 8081 is used by the Metro Bundler. Windows users often face conflicts with McAfee on this port.

Go to http://localhost:8081 →
Kill Port 8081
npx kill-port 8081

React Native vs McAfee Conflict

If Metro Bundler fails to start with EADDRINUSE, it's often McAfee ePO (FrameworkService.exe) hogging port 8081.

Solution 1

Run on Different Port

The easiest fix without touching antivirus settings:

npx react-native start --port=8088

2. Identify the Culprit

On Windows, check if it's really McAfee:

netstat -ano | findstr :8081

Developer Port Reference Guide

Frontend & Web
3000 React / Node / Default 3001 React Secondary 5173 Vite / Vue 3 4200 Angular CLI 8000 Django / Gatsby 8080 Tomcat / Vue / Spring 8081 React Native 80 HTTP Standard 443 HTTPS / SSL
Backend & Infrastructure
5000 Flask / AirPlay 4000 Jekyll / Hexo 9000 SonarQube / PHP
Database & Cache
3306 MySQL 5432 PostgreSQL 27017 MongoDB 6379 Redis 11211 Memcached
DevOps & Data Science
8888 Jupyter Notebook 9200 Elasticsearch 9090 Prometheus 15672 RabbitMQ UI 8500 Consul 127.0.0.1 Loopback IP