Fatal error: Uncaught Error: Interface 'Illuminate\Contracts\Mail\Mailable' not found in C:\xampp\htdocs\admin\vendor\laravel\framework\src\Illuminate\Mail\Mailable.php:21 Stack trace: #0 {main} thrown in C:\xampp\htdocs\admin\vendor\laravel\framework\src\Illuminate\Mail\Mailable.php on line 21