NotFoundHttpException in RouteCollection.php line 161 in laravel

i just wirte code in routes.php as below

 Route::get('/', function () {
    return 'Hello World';
});
Route::get('user/{id}', function ($id) {
    return 'User '.$id;
});
 Route::post('foo/bar', function () {
    return 'Hello World';
});

Route::put('foo/bar', function () {
 //
});

Route::delete('foo/bar', function () {
   //
 });

and it gererate error:... Sorry, the page you are looking for could not be found.NotFoundHttpException in RouteCollection.php line 161:1)in RouteCollection.php line 161.2)at RouteCollection->match(object(Request)) in Router.php line 533 at Router->findRoute(object(Request)) in Router.php line 512. AND OTHER ERROR

via Chebli Mohamed