ErrorException: Declaration of App\Exceptions\Handler::unauthenticated($request, App\Exceptions\AuthenticationException $exception) should be compatible with Illuminate\Foundation\Exceptions\Handler::unauthenticated($request, Illuminate\Auth\AuthenticationException $exception) in file C:\xampp\htdocs\learnlara\app\Exceptions\Handler.php on line 9
Are you upgrading Laravel to a new version? If so go to the laravel/laravel repository and copy the app/Exceptions/Handler.php file to your project. Then everything should be good.
The problem here is that you override the class, but you give it another dependency than the parent class. These two need to match!