next.js/docs/01-app/02-guides/debugging.mdx

---
title: How to use debugging tools with Next.js
nav_title: Debugging
description: Learn how to debug your Next.js application with VS Code, Chrome DevTools, or Firefox DevTools.
---

{/* The content of this doc is shared between the app and pages router. You can use the `<PagesOnly>Content</PagesOnly>` component to add content that is specific to the Pages Router. Any shared content should not be wrapped in a component. */}

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

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 client-side (Firefox)",
      "type": "firefox",
      "request": "launch",
      "url": "http://localhost:3000",
      "reAttach": true,
      "pathMappings": [
        {
          "url": "webpack://_N_E",
          "path": "${workspaceFolder}"
        }
      ]
    },
    {
      "name": "Next.js: debug full stack",
      "type": "node",
      "request": "launch",
      "program": "${workspaceFolder}/node_modules/next/dist/bin/next",
      "runtimeArgs": ["--inspect"],
      "skipFiles": ["<node_internals>/**"],
      "serverReadyAction": {
        "action": "debugWithEdge",
        "killOnServerStop": true,
        "pattern": "- Local:.+(https?://.+)",
        "uriFormat": "%s",
        "webRoot": "${workspaceFolder}"
      }
    }
  ]
}
```

> **Note**: To use Firefox debugging in VS Code, you'll need to install the [Firefox Debugger extension](https://marketplace.visualstudio.com/items?itemName=firefox-devtools.vscode-firefox-debug).

`npm run dev` can be replaced with `yarn dev` if you're using Yarn or `pnpm dev` if you're using pnpm.

In the "Next.js: debug full stack" configuration, `serverReadyAction.action` specifies which browser to open when the server is ready. `debugWithEdge` means to launch the Edge browser. If you are using Chrome, change this value to `debugWithChrome`.

If you're [changing the port number](/docs/pages/api-reference/cli/next#next-dev-options) your application starts on, replace the `3000` in `http://localhost:3000` with the port you're using instead.

If you're running Next.js from a directory other than root (for example, if you're using Turborepo) then you need to add `cwd` to the server-side and full stack debugging tasks. For example, `"cwd": "${workspaceFolder}/apps/web"`.

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 Browser 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 your preferred browser.

For Chrome:

- Open Chrome's Developer Tools (`Ctrl+Shift+J` on Windows/Linux, `⌥+⌘+I` on macOS)
- Go to the **Sources** tab

For Firefox:

- Open Firefox's Developer Tools (`Ctrl+Shift+I` on Windows/Linux, `⌥+⌘+I` on macOS)
- Go to the **Debugger** tab

In either browser, any time your client-side code reaches a [`debugger`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/debugger) statement, code execution will pause and that file will appear in the debug area. You can also search for files to set breakpoints manually:

- In Chrome: Press `Ctrl+P` on Windows/Linux or `⌘+P` on macOS
- In Firefox: Press `Ctrl+P` on Windows/Linux or `⌘+P` on macOS, or use the file tree in the left panel

Note that when searching, your source files will have paths starting with `webpack://_N_E/./`.

### Server-side code

To debug server-side Next.js code with browser 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
```

> **Good to know**: Use `NODE_OPTIONS='--inspect=0.0.0.0'` to allow remote debugging access outside localhost, such as when running the app in a Docker container.

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
```

For Chrome:

1. Open a new tab and visit `chrome://inspect`
2. Click **Configure...** to ensure both debugging ports are listed
3. Add both `localhost:9229` and `localhost:9230` if they're not already present
4. Look for your Next.js application in the **Remote Target** section
5. Click **inspect** to open a separate DevTools window
6. Go to the **Sources** tab

For Firefox:

1. Open a new tab and visit `about:debugging`
2. Click **This Firefox** in the left sidebar
3. Under **Remote Targets**, find your Next.js application
4. Click **Inspect** to open the debugger
5. Go to the **Debugger** tab

Debugging server-side code works similarly to client-side debugging. When searching for files (`Ctrl+P`/`⌘+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).

### Inspect Server Errors with Browser DevTools

When you encounter an error, inspecting the source code can help trace the root cause of errors.

Next.js will display a Node.js icon underneath the Next.js version indicator on the error overlay. By clicking that icon, the DevTools URL is copied to your clipboard. You can open a new browser tab with that URL to inspect the Next.js server process.

### 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)
- [Firefox DevTools: Debugger](https://firefox-source-docs.mozilla.org/devtools-user/debugger/)