error webpack laravel mix

 It's because you have two different versions installed. Over the weekend, the cross-env team changed then path to to their bin directory, which we were referencing. You can fix this by doing npm install cross-env, and then updating your package.json npm script to be:

cross-env NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js