General Information

Warnings:

WCER-W1

Warning, Chrome Extension Reloader Plugin was not enabled! It runs only on webpack --mode=development (before v1.2.3).
Warning, Chrome Extension Reloader Plugin was not enabled! It runs only on webpack --mode=development (v4 or more) or with NODE_ENV=development (lower versions).

This means that the webpack option.mode isn't "development", and the plugin will not be included on the building process. On older versions than v4, use this value on the environment variable NODE_ENV. To not see this warning, make sure to not add this plugin on a non development build, on your Webpack configuration.

WCER-W2

Warning, Chrome browser with unexpected version format. Expected x.x.x.x, Provided $VERSION .

This warning happens when isn't possible to identify the version of the Chrome being used to run the extension. This is important because of the fast reload lock, present on old versions of Chrome. This will cause the extension to fallback into the debounce mode to prevent extension locking. This doesn't cause any errors and the compilation should work just fine.

Errors:

WCER-E1

Background script entry is required. .

The error is raised whenever no background script is provided through the plugin options. Without the background script, Webpack Chrome Extension reloader is unable to access the extension lifecycle through the chrome.runtime to execute the proper extension reload.

entry: {
    //...
    background: './background.js' // *This is required
},
//...
plugins: [
    new ChromeExtensionReloader({
      //...
      entries: { 
        // ...
        background: 'background' // *This is required
      }
    })
]

If your extension don't have background script, at least provide an empty background.js on both manifest.json and Webpack plugin config, on development mode.