webpack抽离css报错，extract-text-webpack-plugin

ERROR in ./src/css/index.scss
Module build failed: Error: “extract-text-webpack-plugin” loader is used without the corresponding plugin, refer to https://github.com/webpack/extract-text-webpack-plugin for the usage example
at Object.pitch (D:\demo_test\webpackDemo\node_modules\extract-text-webpack-plugin\dist\loader.js:57:11)
@ ./src/js/index.js 3:0-28
Child html-webpack-plugin for “index.html”:

ERROR in ./src/css/index.scss
Module build failed: Error: "extract-text-webpack-plugin" loader is used without the corresponding plugin, refer to https://github.com/webpack/extract-text-webpack-plugin for the usage example
    at Object.pitch (D:\demo_test\webpackDemo\node_modules\extract-text-webpack-plugin\dist\loader.js:57:11)
 @ ./src/js/index.js 3:0-28
Child html-webpack-plugin for "index.html":

解决方法：

第一步：

可能原因是webpack版本和extract-text-webpack-plugin版本不对应

"extract-text-webpack-plugin": "^3.0.2",
"webpack": "^3.12.0",
"webpack-dev-server": "^1.14.1"

第二步：

Error: "extract-text-webpack-plugin" loader is used without the corresponding plugin
错误：“extract text webpack plugin”加载程序在没有相应插件的情况下使用

module: {
	rules: [
	  {//css loader 这个地方根据使用的loader配置，我使用的是sass
		test: /\.(css|s[ac]ss)$/,
		use: ExtractTextPlugin.extract({
		  fallback: 'style-loader',
		  use: ['css-loader', 'sass-loader', 'postcss-loader']
		})
	  }
	]
},
// 我的原因是：没有配置下面这个，指定抽离的目录
plugins: [
    new ExtractTextPlugin({ //提取css
      filename: 'css/[name].[hash].css',
      disable: false,
      allChunks: true
    })
  ]