How to retrieve the namespace in Laravel

I changed the namespace from App to SAMM by using command php artisan app:name in Laravel 5.6, but now an error is shown:

Fatal error: Uncaught ReflectionException: Class SAMM\Http\Kernel does
not exist in
/home/vagrant/sites/SAM/vendor/laravel/framework/src/Illuminate/Container/Container.php
on line 767

How could I solve this problem?

via Chebli Mohamed