Invalid Host Header when ngrok tries to connect to React dev server

Title: "🚧 Troubleshooting: Invalid Host Header when ngrok connects to React dev server 🚧"

Introduction

So, you're excited to test your awesome React application on a mobile device, but the moment you try to connect ngrok to the React dev server, you face the dreaded "Invalid Host Header" error. Don't worry! This blog post will guide you through common issues and easy solutions to help you overcome this obstacle and get your app up and running. Let's dive in! 💪

Understanding the Problem

The first thing to understand is that React blocks requests from other sources by default for security reasons. This is known as the "Invalid Host Header" error, as React checks if the Host header matches the current location. When using ngrok, the Host header is modified, causing React to reject the request.

Solution 1️⃣: Configuring ngrok

One way to resolve this issue is by configuring ngrok to modify the Host header to match the React dev server. You can achieve this by adding the host-header option when running ngrok:

ngrok http -host-header="localhost:3000" 3000

This command tells ngrok to modify the Host header to localhost:3000, which is the default address for React dev servers. With this setup, the request should now go through without triggering the "Invalid Host Header" error.

Solution 2️⃣: Using a Proxy

If Solution 1 didn't work for you or you prefer an alternative approach, using a proxy can also solve the problem. Here's how:

1. Install the http-proxy-middleware package by running the following command in your project directory:

npm install http-proxy-middleware

1. Create a new file called setupProxy.js in the src directory of your React project.

2. In setupProxy.js, add the following code:

const { createProxyMiddleware } = require('http-proxy-middleware');

module.exports = function (app) {
  app.use(
    '/api',
    createProxyMiddleware({
      target: 'http://localhost:3000',
      changeOrigin: true,
    })
  );
};

1. Update the target URL in the code to match your React dev server's address.

By adding this proxy configuration, any requests made to /api will be redirected to the React dev server at http://localhost:3000. This bypasses the "Invalid Host Header" error.

Conclusion

Congratulations! You've successfully tackled the "Invalid Host Header" error and can now test your React application on your mobile device using ngrok. Remember, the solutions provided here—configuring ngrok or using a proxy—offer different approaches to overcome this issue.

If you have any questions or need further assistance, feel free to leave a comment below. Happy testing! 🎉

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We hope you found this blog post helpful! If you have any other topics you'd like us to cover or want to share your experiences, leave a comment below. Don't forget to share this post with your tech-savvy friends who may be facing the same issue. Keep exploring and leveling up your tech skills! ✨🚀