I have faced the same issue when memcached was configured for Magento 2. The system was throwing the below error
Warning: ini_set(): Cannot find save handler ‘memcached’ in E:\xampp\htdocs\mage2\vendor\magento\framework\Session\SessionManager.php on line 570
In my case it was due to save_handler value was not udated in php.ini file.
So Make sure that save_handler is modified in php.ini file as well.
Please follow Configure Memcached Magento 2