It is very common. You can make all 777, that will also fail.
Add this to your WordPress wp-config.php file :
define('FS_METHOD','direct');
Basically “myid” in to yourusername to www-data group plus adding www-data group to psaserv group solves it. When you understand running FTP is not safe, you are an advanced user. You should comment out define('FS_METHOD','direct'); after the update.
Thanks for the suggestion. I guess there is no easy way to do this securely. Its not a problem with the small number of sites I have now but will be an issue in the future.