Attempted import error: 'Switch' is not exported from 'react-router-dom' (imported as 'Switch').

  <Switch>
    <Route path="/" exact component={Home}/>
    <Route path="/history" component={History}/>
    <Route path="/about" component={About}/>
  </Switch>

出现报错：Attempted import error: 'Switch' is not exported from 'react-router-dom'
原因：在 react-router-dom 6.0以后 Switch 就不再使用了，修改为新的用法即可（需要注意的是，component也需要修改）

修改为：

   <Routes>
      <Route path="/" exact element={<Home/>}/>
      <Route path="/history" element={<History/>}/>
      <Route path="/about" element={<About/>}/>
   </Routes>