Why is broadcasting/auth not found?

Already uncommented at config/app.php:

AppProvidersBroadcastServiceProvider::class, 

and

IlluminateBroadcastingBroadcastServiceProvider::class,

Error:

POST http://pusherapp.local:8888/broadcasting/auth 404 (Not Found)

I am using Mamp 4 and Laravel 5.5.

Answer

Try this commands

php artisan config:cache
composer require pusher/pusher-php-server "~2.6" (user 2.6 because 3.0 has class Pusher not found issue)
composer update (just to make sure everything is up to date)
php artisan config:cache (do it again)