kcal/app/Http/Middleware/Authenticate.php

<?php

namespace App\Http\Middleware;

use Illuminate\Auth\Middleware\Authenticate as Middleware;

class Authenticate extends Middleware
{
    /**
     * {@inheritdoc}
     */
    protected function redirectTo($request)
    {
        if (!$request->expectsJson()) {
            return route('login');
        }
        return null;
    }
}