extract text plugin - Module build failed: ModuleNotFoundError: Module not found:

Question

I'm using the following module in my webpack config -

{
  test: /\.css$/,
  use: ExtractTextPlugin.extract({
    fallback: "style-loader",
    use: [
      {
        loader: "css-loader",
        options: {
          modules: true,
          localIdentName: "[name]-[local]-[hash:base64:5]"
        }
      },
      {
        loader: "postcss-loader"
      }
    ]
  })
}

I'm getting an error Uncaught Error: Module build failed: ModuleNotFoundError: Module not found: Error: Can't resolve 'shared/variables

It looks like my css can't import files. Any idea what I'm doing wrong?

I'm using webpack 3.5.5 and extract text plugin 3.0.0