Laravel 5 - redirect

Please excuse my bad english level. I'am studying laravel 5 and I have an error with a redirection.

I have a controller with two function:

class MainController extends Controller
{
    public function index() {
        //Some code
        return view('index.main',compact('someDatas');
    }

    public function update(Request $request) {
        //Some code here
        return redirect(route('main'));
    }
}

my route.php

Route::get('/', "main\MainController@index") -> name('main');
Route::get('/update', "main\MainController@update") -> name('update');

In my main.blade.php I have a link with redirection to update:

<a href=""></a>

When i click on the link I have an error :

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.

The URL is https://127.0.0.1:8000/update but when i remove the 's' of HTTPS I'm redirect to main menu.

I don't understand why this error happens, I have other program with similar code and it works.

Thanks for your time and your responses!

via Chebli Mohamed