Error: No supported Encrypter found. The Cipher and / or key length are invalid

Question

Personal I am using Laravel 5.2 and went to perform an authentication, but when I run the command php artisan make:auth works perfectly, but in practice does not... When I click on login or Register give me this error :

No supported Encrypter found. The Cipher and / or key length are invalid.

How can I fix it? Composer.json :

{
    "name": "laravel/laravel",
    "description": "The Laravel Framework.",
    "keywords": ["framework", "laravel"],
    "license": "MIT",
    "type": "project",
    "require": {
        "php": ">=5.5.9",
        "laravel/framework": "5.2.*"

    },
    "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.*"
    },
    "autoload": {
        "classmap": [
            "database"
        ],
        "psr-4": {
            "App\\": "app/"
        }
    },
    "autoload-dev": {
        "classmap": [
            "tests/TestCase.php"
        ]
    },
    "scripts": {
        "post-root-package-install": [
            "php -r \"copy('.env.example', '.env');\""
        ],
        "post-create-project-cmd": [
            "php artisan key:generate"
        ],
        "post-install-cmd": [
            "php artisan clear-compiled",
            "php artisan optimize"
        ],
        "pre-update-cmd": [
            "php artisan clear-compiled"
        ],
        "post-update-cmd": [
            "php artisan optimize"
        ]
    },
    "config": {
        "preferred-install": "dist"
    }
}

Answer 1

Navigated to the project folder and there is no .env.example is because there was some fault in the installation of Laravel, when we first installed Laravel by Composer it generates a copy inside the Composer folder, then create new projects (probably by artesian) it fetches from the local copy, check the folder that has been installed, usually the location that gets saved is the ~/.composer/vendor/bin, if you think something failed in the installation of Composer, use the command this way:

curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/local/bin/composer

When creating a project use the parameter --prefer-dist, thus:

composer create-project --prefer-dist laravel/laravel meuprimeiroprojeto

To check if everything is ok, navigate to the folder typing:

cd meuprimeiroprojeto
ls -a

Will display all files, should appear the .env.example

Answer 2

First of all, you must generate your APP_KEY:

php artisan key:generate

If it’s still not working, check the file config/app.php if it is defined as:

'cipher' => 'AES-256-CBC'

What if the file .env there is... if not, you should rename the .env.example for .env