I had the same error popping up while using <Switch /> inside <Router /> .

Moving the <Switch /> directly above my <Route /> routes fixed it for me. No more warnings! Your post put me in the right direction, so thank you!

My end result:

<Router>
  <Switch>
    <Route exact path="/" component={Component1} {...props} />
    <Route path="/userprofile" render={() => <UserComponent {...props.userProfile} />} />
  </Switch>
</Router>

Thanks!