Laravel: Class 'GuzzleHttp\Client' not found

Question

I am trying to use Mandrill to send emails via my Laravel framework, however I am receiving the following error:

FatalErrorException in MandrillTransport.php line 114: Class 'GuzzleHttp\Client' not found

I have installed Guzzle using the following command in Terminal:

"guzzlehttp/guzzle": "~4.0"

According to Laravel's documentation I need to add "guzzlehttp/guzzle": "~4.0" to my composer.json file, but I'm not sure if where I have placed it is correct as I still see the error.

{
    "name": "laravel/laravel",
    "description": "The Laravel Framework.",
    "keywords": ["framework", "laravel"],
    "license": "MIT",
    "type": "project",
    "require": {
        "laravel/framework": "5.0.*",
        "illuminate/html": "^5.0",
        "guzzlehttp/guzzle": "~4.0"
    },
    "require-dev": {
        "phpunit/phpunit": "~4.0",
        "phpspec/phpspec": "~2.1"
    },
    "autoload": {
        "classmap": [
            "database"
        ],
        "psr-4": {
            "App\\": "app/"
        }
    },
    "autoload-dev": {
        "classmap": [
            "tests/TestCase.php"
        ]
    },
    "scripts": {
        "post-install-cmd": [
            "php artisan clear-compiled",
            "php artisan optimize"
        ],
        "post-update-cmd": [
            "php artisan clear-compiled",
            "php artisan optimize"
        ],
        "post-create-project-cmd": [
            "php -r \"copy('.env.example', '.env');\"",
            "php artisan key:generate"
        ]
    },
    "config": {
        "preferred-install": "dist"
    }
}

Here is the list of packages my application has, notice that guzzle has a different version: 4.2.3 which i've also tried updating to but still get the same error.

Answer 1

Open up your terminal at the root of your project and enter

composer require guzzlehttp/guzzle

It worked for the mailgun API. For some reason, the suggested method at the laravel's mail doc. You may install this package to your project by adding the following line to your composer.json file

"guzzlehttp/guzzle": "~5.3|~6.0"

doesn't make the composer download the Guzzle source codes. By the way, I didn't find out what | means in determining the version. This command just downloads the PSR code.

In this moment, the solution may work. However, be aware of compatibility issues. Because the command would install the latest stable version, not the suitable one.