title: Webpack Upgrade - Module not found: Can't resolve node_modules
body: <p>I'm currently working on a upgrade from Webpack 1 to 2, and then to 3. Within this upgrade, I've adhered to the migration instructions as per the instructions for <a href="https://webpack.js.org/guides/migrating/" rel="noreferrer"><strong>1 => 2</strong></a> and for <a href="https://medium.com/webpack/webpack-3-official-release-15fd2dd8f07b" rel="noreferrer"><strong>2 => 3</strong></a>. </p>
  
  <p>The issue I'm having is that none of the installed packages within my <code>node_modules</code> seem to be getting resolved within my code inside <code>client/app/bundles</code>. The error I'm getting for all the node_modules are in the following structure:</p>
  
  <blockquote>
    <p>ERROR in ./node_modules/alt/lib/store/StoreMixin.js || 
      Module not found: Error: Can't resolve 'transmitter' in 'client/node_modules/alt/lib/store'</p>
  </blockquote>
  
  <p>My theory is that somewhere I have a mismatch on the <code>file-loader</code>, <code>expose-loader</code>, or <code>imports-loader</code> versions since it makes sense that without the proper versions, the modules wouldn't get imported. I've ensured that all the <code>module.rules</code> have loaders that end in the <code>-loader</code> pattern. <code>yarn install</code> also succeeds without errors.</p>
  
  <p>My dependencies and Webpack configurations are as follows:</p>
  
  <h1>Package.json</h1>
  
  <pre><code>"dependencies": {
      "ajv": "^5.1.5",
      "alt": "^0.17.8",
      "alt-container": "^1.0.2",
      "autoprefixer": "^6.4.0",
      "axios": "^0.7.0",
      "babel-cli": "^6.10.1",
      "babel-core": "^6.3.26",
      "babel-loader": "^7.1.2",
      "babel-plugin-syntax-decorators": "^6.3.13",
      "babel-polyfill": "^6.3.14",
      "babel-preset-es2015": "^6.3.13",
      "babel-preset-react": "^6.3.13",
      "babel-preset-stage-0": "^6.3.13",
      "babel-types": "^6.4.5",
      "body-parser": "^1.14.1",
      "chai": "^3.4.1",
      "chai-enzyme": "^0.6.1",
      "css-loader": "^0.23.1",
      "enzyme": "^2.5.0",
      "es5-shim": "^4.1.14",
      "es6-promise": "^3.0.2",
      "expose-loader": "^0.7.1",
      "fbjs": "^0.8.16",
      "file-loader": "^1.1.5",
      "fixed-data-table-2": "^0.7.11",
      "immutable": "^3.7.5",
      "imports-loader": "^0.6.5",
      "jade": "^1.11.0",
      "jquery": "^2.1.4",
      "jquery-ujs": "^1.1.0-1",
      "jsdom": "^7.0.2",
      "loader-utils": "^0.2.11",
      "lodash": "^4.11.1",
      "lodash-uuid": "^0.0.3",
      "mocha-jsdom": "^1.0.0",
      "moment": "^2.11.1",
      "postcss-loader": "^0.10.1",
      "react": "^15.6.1",
      "react-addons-test-utils": "15.4.0",
      "react-bootstrap": "^0.30.3",
      "react-dnd": "^2.5.4",
      "react-dnd-html5-backend": "^2.0.0",
      "react-dnd-test-backend": "^1.0.0",
      "react-dom": "^15.6.1",
      "react-fa": "^4.1.2",
      "react-height": "^3.0.0",
      "react-json-tree": "^0.10.9",
      "react-on-rails": "10.0.0",
      "react-onclickoutside": "^5.7.0",
      "react-overlays": "^0.6.2",
      "react-select": "^1.0.0-rc.3",
      "react-table": "^6.0.5",
      "react-textarea-autosize": "^4.0.5",
      "sass-loader": "^6.0.6",
      "sinon": "^1.17.2",
      "sinon-chai": "^2.8.0",
      "sleep": "^3.0.0",
      "source-map": "^0.6.1",
      "uglify-js": "^2.8.29",
      "url-loader": "^0.5.6",
      "webpack": "^3.1.0",
      "webpack-dev-server": "^2.9.2"
    },
    "devDependencies": {
      "babel-eslint": "^6.1.0",
      "babel-istanbul": "^0.11.0",
      "babel-plugin-react-transform": "^2.0.0",
      "bootstrap-loader": "^2.0.0",
      "bootstrap-sass": "^3.3.6",
      "eslint": "^3.3.0",
      "eslint-config-airbnb": "^10.0.1",
      "eslint-config-shakacode": "^0.0.1",
      "eslint-plugin-import": "^1.13.0",
      "eslint-plugin-jsx-a11y": "^2.1.0",
      "eslint-plugin-react": "^6.0.0",
      "esprima-fb": "^15001.1001.0-dev-harmony-fb",
      "express": "^4.13.3",
      "extract-text-webpack-plugin": "3.0.1",
      "image-webpack-loader": "^3.1.0",
      "mocha": "^2.3.3",
      "mocha-jenkins-reporter": "^0.1.9",
      "mocha-jsdom": "^1.0.0",
      "node-sass": "4.0.0",
      "react-loadable": "^5.3.0",
      "react-transform-hmr": "^1.0.1",
      "resolve-url-loader": "^1.4.3",
      "style-loader": "^0.19.0",
      "stylelint": "^7.1.0",
      "stylelint-config-standard": "^12.0.0"
  }
  </code></pre>
  
  <h1>File Structure</h1>
  
  <pre><code>webpack.client.rails.config.js
  app
      /assets
          /javascripts
              /generated
              -- app-bundle.js
              -- vendor-bundle.js
  client
      /app
          /bundles
              /[APP ENTRY]...
      /node_modules
      webpack.client.rails.config.js
      webpack.client.base.config.js
  </code></pre>
  
  <h1>webpack.client.rails.config.js</h1>
  
  <pre><code>const webpack = require('webpack');
  const path = require('path');
  const config = require('./webpack.client.base.config');
  
  const devBuild = process.env.NODE_ENV !== 'production';
  
  const autoprefixer = require('autoprefixer');
  
  config.output = {
    filename: '[name]-bundle.js',
    path: path.resolve('../app/assets/javascripts/generated'),
    publicPath: path.resolve('/assets/generated/'),
  };
  
  config.entry.vendor.unshift(
    'es5-shim/es5-shim',
    'es5-shim/es5-sham'
  );
  
  config.entry.vendor.push('jquery-ujs');
  
  config.module.rules.push(
    {
      test: /\.jsx?$/,
      loader: 'babel-loader',
      exclude: /node_modules/,
    },
    {
      test: require.resolve('react'),
      loader: 'imports-loader?shim=es5-shim/es5-shim&amp;sham=es5-shim/es5-sham',
    },
    {
      test: require.resolve('jquery-ujs'),
      loader: 'imports-loader?jQuery=jquery',
    },
    {
      test: /\.css$/,
      loader: 'style-loader!css-loader',
    },
    {
      test: /\.scss$/,
      use: [
        'style-loader',
        'css-loader',
        {
          loader: 'postcss-loader',
          options: {
            plugins: function() {
              return [autoprefixer]
            }
          }
        },
        'sass-loader',
      ],
      exclude: /assets\/stylesheets\/common\/packages\/DocumentEditor/,
    },
    {
      test: /\.scss$/,
      use: [
        'style-loader?{"singleton":true,"attrs":{"id":"document-content-stylesheet"}}',
        'css-loader',
        {
          loader: 'postcss-loader',
          options: {
            plugins: function() {
              return [autoprefixer]
            }
          }
        },
        'sass-loader',
      ],
      include: /assets\/stylesheets\/common\/packages\/DocumentEditor/,
    },
    {
      test: /\.(ttf|eot|svg)(\?v=[0-9]\.[0-9]\.[0-9])?$/,
      loader: 'file-loader',
    },
    {
      test: /\.woff(2)?(\?v=[0-9]\.[0-9]\.[0-9])?$/,
      loader: 'url-loader?limit=10000&amp;mimetype=application/font-woff',
    }
  );
  
  module.exports = config;
  
  if (devBuild) {
    console.log('Webpack dev build for Rails'); // eslint-disable-line no-console
    module.exports.devtool = 'eval-source-map';
  } else {
    config.plugins.push(
      new webpack.optimize.DedupePlugin()
    );
    console.log('Webpack production build for Rails'); // eslint-disable-line no-console
  }
  </code></pre>
  
  <h1>webpack.client.base.config.js</h1>
  
  <pre><code>const webpack = require('webpack');
  const path = require('path');
  const aliases = require('./aliases');
  
  const devBuild = process.env.NODE_ENV !== 'production';
  const nodeEnv = devBuild ? 'development' : 'production';
  
  module.exports = {
  
    context: __dirname,
    entry: {
  
      vendor: [
        'babel-polyfill',
        'jquery',
      ],
  
      app: [
        './app/bundles/BundleOne/startup/clientRegistration',
        './app/bundles/BundleTwo/startup/clientRegistration',
        './app/bundles/BundleThree/startup/clientRegistration',
        './app/bundles/BundleFour/startup/clientRegistration',
        './app/bundles/BundleFive/startup/clientRegistration',
        './app/bundles/BundleSix/startup/clientRegistration',
        './app/bundles/BundleSeven/startup/clientRegistration',
      ],
    },
    resolve: {
      modules: [
        path.resolve('./app/bundles'),
      ],
      extensions: ['.js', '.jsx'],
      alias: aliases,
    },
    plugins: [
      new webpack.DefinePlugin({
        'process.env': {
          NODE_ENV: JSON.stringify(nodeEnv),
        },
      }),
  
      new webpack.optimize.CommonsChunkPlugin({
        name: 'vendor',
        filename: 'vendor-bundle.js',
        minChunks: Infinity,
      }),
    ],
    module: {
      rules: [
        { test: require.resolve('jquery'), loader: 'expose-loader?jQuery' },
        { test: require.resolve('jquery'), loader: 'expose-loader?$' },
      ],
    },
  };
  </code></pre>