Check the render method of `Router .Consumer`?

index.js file

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

ReactDOM.render(
  <App />,
  document .get Element By Id('root')
);

error

Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object.

Check the render method of Router .Consumer.

I have no idea how to fix this?