Solution - "extract-text-webpack-plugin" loader is used without the corresponding plugin

Using loaders instead of rules as part of a module configuration in Webpack 2.

In Webpack 2.1 you must switch loaders to rules as part of a module configuration.

# DON'T DO
module.exports = {
    //...
    module: {
        loaders: [
# DO
module.exports = {
    //...
    module: {
        rules: [
    	        

Declaring ExtractTextPlugin instance with constant

Declare ExtractTextPlugin instance with name variable

# DON'T DO
new ExtractTextPlugin ("style.css",
                        {allChunks: true}))
# DO
new ExtractTextPlugin("[name].css",
                        {allChunks: true})
    	        

Using ExtractTextPlugin in combination with HtmlWebpackPlugin and using underscore-template-loader as part of a template definition

Don't use underscore-template-loader as part of a template definition

# DON'T DO
new HtmlWebpackPlugin({
  template: 'underscore-template-loader!./src/index.html',
  ...
  });
# DO
new HtmlWebpackPlugin({
  template: './src/index.html',
  ...
  });
    	        

Using an old HappyPack plugin version

Upgrade to new HappyPack plugin version

Using Node 6.0.0 or higher

Downgrade to a version of Node earlier than 6.0.0

# Check node version
node -v
# Clean up cache and install node 5.12.0
sudo npm cache clean -f
sudo npm install -g n
sudo n 5.12.0
# All node version numbers available at
# https://nodejs.org/en/download/releases/
# To return to latest stable Node version
# if previous solution didn't work do:
# sudo n stable