After install Magento2.2 using the .tar into a nanobox and setting up via /setup, the admin page and home page give an error Fatal error: Class ‘SessionHandler’ not found in /app/vendor/magento/framework/Session/SaveHandler/Native.php on line 11 My boxfile.yml, which sets up the environment, modules, extensions etc looks like this: run.config: engine: php engine.config: session_save_handler: ‘files’ session_save_path: ‘var/session’Read more