I did a composer upgrade from 2.06 to 2.07 and now get this message when trying to access the site admin pages! Doesn't even load the login screen.
Fatal error: Class 'Magento\Framework\Code\Generator\Autoloader' not found in /var/sites/e/***.co.uk/public_html/vendor/magento/framework/ObjectManager/DefinitionFactory.php on line 104
You can check this link,
You may get some help
It's possible that it's a permissions or a file ownership issue. Have you tried running chmod and changing the owner to the Apache/Nginx user?