---
title: Debugging
description: Learn how to debug your Next.js application with VS Code or Chrome DevTools.
---

This documentation explains how you can debug your Next.js frontend and backend code with full source maps support using either the [VS Code debugger](https://code.visualstudio.com/docs/editor/debugging) or [Chrome DevTools](https://developers.google.com/web/tools/chrome-devtools).

Any debugger that can attach to Node.js can also be used to debug a Next.js application. You can find more details in the Node.js [Debugging Guide](https://nodejs.org/en/docs/guides/debugging-getting-started/).

## Debugging with VS Code

Create a file named `.vscode/launch.json` at the root of your project with the following content:

```json filename="launch.json"
{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Next.js: debug server-side",
      "type": "node-terminal",
      "request": "launch",
      "command": "npm run dev"
    },
    {
      "name": "Next.js: debug client-side",
      "type": "chrome",
      "request": "launch",
      "url": "http://localhost:3000"
    },
    {
      "name": "Next.js: debug full stack",
      "type": "node-terminal",
      "request": "launch",
      "command": "npm run dev",
      "serverReadyAction": {
        "pattern": "started server on .+, url: (https?://.+)",
        "uriFormat": "%s",
        "action": "debugWithChrome"
      }
    }
  ]
}
```

`npm run dev` can be replaced with `yarn dev` if you're using Yarn. If you're [changing the port number](/docs/pages/api-reference/next-cli#development) your application starts on, replace the `3000` in `http://localhost:3000` with the port you're using instead.

Now go to the Debug panel (`Ctrl+Shift+D` on Windows/Linux, `⇧+⌘+D` on macOS), select a launch configuration, then press `F5` or select **Debug: Start Debugging** from the Command Palette to start your debugging session.

## Using the Debugger in Jetbrains WebStorm

Click the drop down menu listing the runtime configuration, and click `Edit Configurations...`. Create a `Javascript Debug` debug configuration with `http://localhost:3000` as the URL. Customize to your liking (e.g. Browser for debugging, store as project file), and click `OK`. Run this debug configuration, and the selected browser should automatically open. At this point, you should have 2 applications in debug mode: the NextJS node application, and the client/ browser application.

## Debugging with Chrome DevTools

### Client-side code

Start your development server as usual by running `next dev`, `npm run dev`, or `yarn dev`. Once the server starts, open `http://localhost:3000` (or your alternate URL) in Chrome. Next, open Chrome's Developer Tools (`Ctrl+Shift+J` on Windows/Linux, `⌥+⌘+I` on macOS), then go to the **Sources** tab.

Now, any time your client-side code reaches a [`debugger`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/debugger) statement, code execution will pause and that file will appear in the debug area. You can also press `Ctrl+P` on Windows/Linux or `⌘+P` on macOS to search for a file and set breakpoints manually. Note that when searching here, your source files will have paths starting with `webpack://_N_E/./`.

### Server-side code

To debug server-side Next.js code with Chrome DevTools, you need to pass the [`--inspect`](https://nodejs.org/api/cli.html#cli_inspect_host_port) flag to the underlying Node.js process:

```bash filename="Terminal"
NODE_OPTIONS='--inspect' next dev
```

If you're using `npm run dev` or `yarn dev` then you should update the `dev` script on your `package.json`:

```json filename="package.json"
{
  "scripts": {
    "dev": "NODE_OPTIONS='--inspect' next dev"
  }
}
```

Launching the Next.js dev server with the `--inspect` flag will look something like this:

```bash filename="Terminal"
Debugger listening on ws://127.0.0.1:9229/0cf90313-350d-4466-a748-cd60f4e47c95
For help, see: https://nodejs.org/en/docs/inspector
ready - started server on 0.0.0.0:3000, url: http://localhost:3000
```

> Be aware that running `NODE_OPTIONS='--inspect' npm run dev` or `NODE_OPTIONS='--inspect' yarn dev` won't work. This would try to start multiple debuggers on the same port: one for the npm/yarn process and one for Next.js. You would then get an error like `Starting inspector on 127.0.0.1:9229 failed: address already in use` in your console.

Once the server starts, open a new tab in Chrome and visit `chrome://inspect`, where you should see your Next.js application inside the **Remote Target** section. Click **inspect** under your application to open a separate DevTools window, then go to the **Sources** tab.

Debugging server-side code here works much like debugging client-side code with Chrome DevTools, except that when you search for files here with `Ctrl+P` or `⌘+P`, your source files will have paths starting with `webpack://{application-name}/./` (where `{application-name}` will be replaced with the name of your application according to your `package.json` file).

### Debugging on Windows

Windows users may run into an issue when using `NODE_OPTIONS='--inspect'` as that syntax is not supported on Windows platforms. To get around this, install the [`cross-env`](https://www.npmjs.com/package/cross-env) package as a development dependency (`-D` with `npm` and `yarn`) and replace the `dev` script with the following.

```json filename="package.json"
{
  "scripts": {
    "dev": "cross-env NODE_OPTIONS='--inspect' next dev"
  }
}
```

`cross-env` will set the `NODE_OPTIONS` environment variable regardless of which platform you are on (including Mac, Linux, and Windows) and allow you to debug consistently across devices and operating systems.

> **Good to know**: Ensure Windows Defender is disabled on your machine. This external service will check _every file read_, which has been reported to greatly increase Fast Refresh time with `next dev`. This is a known issue, not related to Next.js, but it does affect Next.js development.

## More information

To learn more about how to use a JavaScript debugger, take a look at the following documentation:

- [Node.js debugging in VS Code: Breakpoints](https://code.visualstudio.com/docs/nodejs/nodejs-debugging#_breakpoints)
- [Chrome DevTools: Debug JavaScript](https://developers.google.com/web/tools/chrome-devtools/javascript)
