I recently upgrade Laravel 5.3 to Laravel 5.4. I had read the upgrade guide provided by the laravel, and everything looks good. Until I try to run the Laravel Tinker and it\
Laravel Tinker
In order to continue using the tinker Artisan command, you should also install the laravel/tinker package:
composer require laravel/tinker
Once the package has been installed, you should add
Laravel\Tinker\TinkerServiceProvider::class
to the providers array in your config/app.php configuration file.
Source: https://laravel.com/docs/5.4/upgrade