title: error vendor\laravel\framework\src\Illuminate\Container\Container.php:833 in laravel
body: <p>please help me, I'm learning and using Laravel 8.x . I don't know what is my error in this case.
  ...</p>
  <pre><code>vendor\laravel\framework\src\Illuminate\Container\Container.php:833
  </code></pre>
  <p>...</p>
  <p>this is my controller</p>
  <pre><code>&lt;?php
  
  namespace App\Http\Controllers;
  
  use Illuminate\Http\Request;
  
  class AdminController extends Controller
  {
      public function index(){
          echo'admin';
      }
  }
  </code></pre>
  <p>and this is my web.php</p>
  <pre><code>&lt;?php
      
  use Illuminate\Support\Facades\Route;
  
  Route::get('/admin','AdminController@index');
  </code></pre>