Créer une interface d’administration dans Magento 2

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="admin">
        <route id="mymodule" frontName="mymodule">
            <module name="Gone_MyModule" />
        </route>
    </router>
</config>

<?php
namespace Gone\MyModule\Controller\Adminhtml;

use Magento\Backend\App\Action;
use Magento\Framework\View\Result\PageFactory;

class Index extends Action
{
    protected $resultPageFactory;

    public function __construct(Action\Context $context, PageFactory $resultPageFactory)
    {
        $this->resultPageFactory = $resultPageFactory;
        parent::__construct($context);
    }

    public function execute()
    {
        $resultPage = $this->resultPageFactory->create();
        $resultPage->getConfig()->getTitle()->prepend(__('My Admin Page'));

        return $resultPage;
    }
}

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Backend:etc/menu.xsd">
    <menu>
        <add id="Gone_MyModule::my_page" title="My Page" module="Gone_MyModule" sortOrder="999" resource="Magento_Backend::content" action="mymodule/mypage/index" />
    </menu>
</config>

php bin/magento cache:clean