# Debugging the Main Process The browser window DevTools can only debug the renderer process scripts (i.e. the web pages). In order to provide a way to debug the scripts from the main process, Electron has provided the `--debug` and `--debug-brk` switches. ## Command Line Switches Use the following command line switches to debug Electron's main process: ### `--debug=[port]` When this switch is used Electron will listen for V8 debugger protocol messages on the `port`. The default `port` is `5858`. ### `--debug-brk=[port]` Like `--debug` but pauses the script on the first line. ## Use node-inspector for Debugging **Note:** Electron doesn't currently work very well with node-inspector, and the main process will crash if you inspect the `process` object under node-inspector's console. ### 1. Install the [node-gyp required tools][node-gyp-required-tools] ### 2. Install [node-inspector][node-inspector] ```bash $ npm install node-inspector ``` ### 3. Install [node-pre-gyp][node-pre-gyp] ```bash $ npm install node-pre-gyp ``` ### 4. Recompile the `node-inspector` `v8` modules for Electron **Note:** Update the target argument to be your Electron version number ```bash $ node_modules/.bin/node-pre-gyp --target=1.2.5 --runtime=electron --fallback-to-build --directory node_modules/v8-debug/ --dist-url=https://atom.io/download/atom-shell reinstall $ node_modules/.bin/node-pre-gyp --target=1.2.5 --runtime=electron --fallback-to-build --directory node_modules/v8-profiler/ --dist-url=https://atom.io/download/atom-shell reinstall ``` See also [How to install native modules][how-to-install-native-modules]. ### 5. Enable debug mode for Electron You can either start Electron with a debug flag like: ```bash $ electron --debug=5858 your/app ``` or, to pause your script on the first line: ```bash $ electron --debug-brk=5858 your/app ``` ### 6. Start the [node-inspector][node-inspector] server using Electron ```bash $ ELECTRON_RUN_AS_NODE=true path/to/electron.exe node_modules/node-inspector/bin/inspector.js ``` ### 7. Load the debugger UI Open http://127.0.0.1:8080/debug?ws=127.0.0.1:8080&port=5858 in the Chrome browser. You may have to click pause if starting with `debug-brk` to see the entry line. [node-inspector]: https://github.com/node-inspector/node-inspector [node-pre-gyp]: https://github.com/mapbox/node-pre-gyp [node-gyp-required-tools]: https://github.com/nodejs/node-gyp#installation [how-to-install-native-modules]: using-native-node-modules.md#how-to-install-native-modules