Have run laravel docker shift from 5.3 to 5.4 and 5.4 to 5.5 with problems

When running composer update it works until @php artisan package:discover I then got: In ProviderRepository.php line 208: Class 'Barryvdh\Cors\ServiceProvider' not found
Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

I got Barryvdh\Cors\ServiceProvider class defined in app.php

So php artisan does not work at all. So what could be the problem?

via Chebli Mohamed