How to Solve Nodemon Restart Issues in Node.js

If you’ve encountered a scenario where Nodemon fails to restart your Node.js server properly after saving changes getting stuck on “restarting due to changes” you’re not alone. This common issue often stems from misconfigurations or errors in your code that prevent the server from relaunching cleanly. Let’s break down the problem and walk through practical solutions to get Nodemon working smoothly again.

Understanding the Problem

In your case, Nodemon detects file changes and attempts to restart the server, but it hangs indefinitely instead of reloading. The root cause often lies in one of the following:

1. Missing or misconfigured dependencies (e.g., body-parser not installed).
2. Errors in code logic (e.g., undefined variables).
3. Port conflicts or logging inconsistencies.
4. Improper Nodemon setup (global vs. local installation conflicts).

Let’s dissect your setup to identify the culprits.

Fix Dependency Issues

Your package.json incorrectly lists body-parser under scripts instead of dependencies. This means body-parser isn’t actually installed, causing your server to crash when it tries to load the module.

Fix this by:

• Moving body-parser to dependencies:

"dependencies": {
  "express": "^4.18.2",
  "nodemon": "^3.1.9",
  "body-parser": "^1.20.1"
}

• Run npm install to install missing dependencies.

Correct Code Errors

Your server.js references jsonParser, but it’s never defined. This throws an error and crashes the server on startup.

Update the code to:

const bodyParser = require('body-parser');
const jsonParser = bodyParser.json(); // Define jsonParser

server.get('/', jsonParser, (req, res) => {
  res.sendFile(__dirname + '/index.html');
});

Resolve Port Conflicts

Your server listens on port 5002, but the log message says port 5000. While this doesn’t break the server, it’s misleading. Ensure consistency:

const port = '5000'; // Match the log message
server.listen(port, (e) => 
  console.log(`Server listening on port ${port}`)
);

This avoids confusion and ensures you’re monitoring the correct port.

Configure Nodemon Correctly

While you’ve installed Nodemon globally and locally, it’s best to use it via an npm script to avoid version conflicts. Update your package.json scripts:

"scripts": {
  "start": "node server.js",
  "dev": "nodemon server.js"
}

Now run the server with:

npm run dev

Check for Silent Errors

If your server crashes on startup (e.g., due to missing dependencies), Nodemon might restart it repeatedly without displaying the error. Add error handling to server.listen():

server.listen(port, (e) => {
  if (e) {
    console.error("Failed to start server:", e);
    process.exit(1); // Exit explicitly on error
  }
  console.log(`Server listening on port ${port}`);
});

This ensures errors are logged, making debugging easier.

Final Thoughts

Nodemon is a powerful tool, but it relies on your server starting up cleanly. The key takeaways for resolving restart issues are:

1. Validate dependencies: Ensure all required packages are listed in dependencies and installed.
2. Fix code errors: Undefined variables or syntax issues crash the server silently.
3. Use Nodemon via npm scripts: Avoid global/local conflicts.
4. Handle errors explicitly: Log errors to catch issues early.

After applying these fixes, Nodemon should restart your server seamlessly. If problems persist, try:

• Killing existing Node processes: killall node (Linux/macOS) or taskkill /im node.exe /f (Windows).
• Using the --verbose flag with Nodemon: nodemon --verbose server.js.

By addressing these common pitfalls, you’ll streamline your development workflow and spend less time debugging restarts!