# Next.js WebSocket Fix

## Issue

In Next.js 14.2.3, there's an issue with the WebSocket server used for Hot Module Replacement (HMR). You might see the following error when running the development server:

```
Error handling upgrade request TypeError: wsServer.handleUpgrade is not a function
    at HotReloaderWebpack.onHMR (/path/to/node_modules/next/dist/server/dev/hot-reloader-webpack.js:345:18)
    at upgradeHandler (/path/to/node_modules/next/dist/server/lib/router-server.js:451:59)
    at Server.<anonymous> (/path/to/node_modules/next/dist/server/lib/start-server.js:170:19)
```

## What Causes This?

The error occurs because the WebSocket server (`wsServer`) is referenced directly in the HotReloaderWebpack's `onHMR` method, but it's not properly initialized.

## How We Fixed It

We created a patch script at `scripts/fix-nextjs-ws.js` that modifies the Next.js hot-reloader-webpack.js file to properly initialize the WebSocket server.

The script is automatically run:
1. After `npm install` through the postinstall hook in package.json
2. Manually if needed by running `node scripts/fix-nextjs-ws.js`

## Manual Fix (if needed)

If you encounter this error, you can run:

```bash
node scripts/fix-nextjs-ws.js
```

This will patch the Next.js file. After applying the patch, restart your development server.

## Technical Details

The patch adds the following code to the `onHMR` method in `hot-reloader-webpack.js`:

```javascript
// Create WebSocket server if not available
const WebSocketServer = require("ws").Server;
const wsServer = new WebSocketServer({ noServer: true });
```

This initializes the WebSocket server before it's used, which resolves the error.

## Future Updates

When upgrading Next.js, you may need to re-apply this patch. The postinstall script should handle this automatically, but if you encounter WebSocket errors after an upgrade, run the fix script manually.