Can't install Cashier ~6.0 on Laravel 5.2

Question

I'm following the instructions via https://laravel.com/docs/5.2/billing to setup cashier and hopefully Stripe!

Here's a portion of my composer.json

"type": "project",
    "require": {
        "php": ">=5.5.9",
        "laravel/framework": "5.2.*",
        "laravel/cashier": "~6.0"
    },
    "require-dev": {
        "fzaninotto/faker": "~1.4",
        "mockery/mockery": "0.9.*",
        "phpunit/phpunit": "~4.0",
        "symfony/css-selector": "2.8.*|3.0.*",
        "symfony/dom-crawler": "2.8.*|3.0.*"
    },

Here's my evidence that Cashier is in (via terminal)

./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Removing laravel/cashier (v6.0.0)
  - Installing laravel/cashier (v6.0.17)
    Downloading: 100%         

Writing lock file
Generating autoload files
> Illuminate\Foundation\ComposerScripts::postUpdate
> php artisan optimize
Generating optimized class loader

And here's a portion of my /config/app.php

 Illuminate\Auth\Passwords\PasswordResetServiceProvider::class,
 Illuminate\Session\SessionServiceProvider::class,
 Illuminate\Translation\TranslationServiceProvider::class,
 Illuminate\Validation\ValidationServiceProvider::class,
 Illuminate\View\ViewServiceProvider::class,
 Laravel\Cashier\CashierServiceProvider::class,

and then the error

FatalErrorException in ProviderRepository.php line 146:
Class 'Laravel\Cashier\CashierServiceProvider' not found

I've ran the following commands

• php artisan : to see if cashier is available and it is not
• composer update but there's nothing to update
• composer require laravel/cashier=~6.0 but there's nothing to update

Answer 1

php artisan optimize
php artisan config:cache
php artisan route:cache 

Try these commands, and run composer install && composer update.