Fatal error: Uncaught Error: Class 'Magento\Framework\Serialize\Serializer\Json' not found in /html/magento2/vendor/magento/framework/ObjectManager/Factory/Compiled.php:60 Stack trace: #0 /html/magento2/vendor/magento/framework/ObjectManager/Factory/Compiled.php(150): Magento\Framework\ObjectManager\Factory\Compiled->create('Magento\\Framewo...') #1 /html/magento2/vendor/magento/framework/ObjectManager/Factory/Compiled.php(79): Magento\Framework\ObjectManager\Factory\Compiled->get('Magento\\Framewo...') #2 /html/magento2/vendor/magento/framework/ObjectManager/ObjectManager.php(70): Magento\Framework\ObjectManager\Factory\Compiled->create('Magento\\Framewo...') #3 /html/magento2/vendor/magento/framework/Interception/Config/Config.php(117): Magento\Framework\ObjectManager\ObjectManager->get('Magento\\Framewo...') #4 /html/magento2/vendor/magento/framework/ObjectManager/Factory/AbstractFactory.php(121): Magento\Framework\Interception\Config\Config->__construct(Object(Magento\Framework\ObjectManager\Config\Reader\Dom\Proxy), in /html/magento2/vendor/magento/framework/ObjectManager/Factory/Compiled.php on line 60