troubleshooting

resolving

general resolving issues

• --display-error-details give you more details.
• Read Configuration regarding resolving starting at resolve
• loaders have their own resolving configuration resolveLoader

npm linked modules don't find their dependencies

The node.js module-resolving algorithm is pretty simple: module dependencies are looked up in node_modules folders in every parent directory of the requiring module. When you npm link modules with peer dependencies that are not in your root directory, modules can no longer be found. (You probably want to consider peerDependencies with npm link as broken by design in node.js.) Note that a dependency to the application (even if this is not the perfect design) is also a kind of peer dependency even if it's not listed as such in the module's package.json.

But you can easily work around that in webpack: add the node_modules folder of your application to the resolve paths. There are two config options for this: resolve.fallback and resolveLoader.fallback.

Here is a config example:

module.exports = {
  resolve: { fallback: path.join(__dirname, "node_modules") },
  resolveLoader: { fallback: path.join(__dirname, "node_modules") }
};

Watching

webpack doesn't recompile on change while watching

File changes are being seen, just no files are being updated

Verify that webpack is not being notified of changes by running with the --progress flag. If progress shows on save but no files are output, it is likely a configuration issue, not a file watching issue.

webpack --watch --progress

Not enough watchers

Verify that if you have enough available watchers in your system. If this value is too low, the file watcher in Webpack won't recognize the changes:

cat /proc/sys/fs/inotify/max_user_watches

Arch users, add fs.inotify.max_user_watches=524288 to /etc/sysctl.d/99-sysctl.conf and then execute sysctl --system. Ubuntu users (and possibly others): echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p.

macOS fsevents bug

On macOS folders can get corrupted. See this article:

OS X FSEvents bug may prevent monitoring of certain folders

Windows paths

webpack expects absolute paths for many config options. __dirname + "/app/folder" is wrong, because windows uses \ as path separator. This breaks some stuff.

Use the correct separators. I.e. path.resolve(__dirname, "app/folder") or path.join(__dirname, "app", "folder").

Vim

On some machines Vim is preconfigured with the backupcopy option set to auto. This could potentially cause problems with the system's file watching mechanism. Switching this option to yes will make sure a copy of the file is made and the original one overwritten on save.

:set backupcopy=yes

File saves in WebStorm don't trigger the watcher

When using the JetBrains WebStorm IDE, you may find that saving changed files does not trigger the watcher as you might expect. Try disabling the safe write option in the settings, which determines whether files are saved to a temporary location first before the originals are overwritten: uncheck File > Settings... > System Settings > Use "safe write" (save changes to a temporary file first).