You should make sure that in app/Http/Kernel.php in middlewareGroups property for web you have:
\Illuminate\View\Middleware\ShareErrorsFromSession::class,
在这个数组中.把这个和https://github.com/laravel/laravel/blob/master/app/Http/Kernel.php相比
EDIT
It seems you need to add 'middleware' => 'web' for route you are using or put \Illuminate\View\Middleware\ShareErrorsFromSession::class, into $middleware property array
or
在routes.php文件内部，try 在以下挡路内创建路径
Route::group(['middleware' => ['web']], function () {
//routes here
});
UPDATE FOR NEWER VERSIONS OF LARAVEL APPLICATION
Be aware that you might run into problems also in case you use web middleware twice. There was a change in Laravel application 5.2.27 (don't confuse it with Laravel framework you use at the moment - you might use Laravel framework for example 5.2.31 but have Laravel application in version 5.2.24) in which web middleware is applied automatically for all routes. So in case of problems, you should open your app/Providers/RouteServiceProvider.php file and verify its content.
您还可以在这里进行比较:
In case you have newer version (that applies web middleware automatically), you shouldn't use web middleware in routes.php anymore or you should modify your RouteServiceProvider method to not apply web group middleware. Otherwise if web middleware group is automatically applied in this provider and you use it also in routes.php you might get very unexpected results.