Comment 4 for bug 1571668

Thank you, indeed I had the suspicion that some kind of local socket authentication might've been disabled, instead of changing the password.

> I think it's something else - please see below. Based on this, you should be able to change the root password to something non-empty with "sudo dpkg-reconfigure mysql-server-5.7" and then logging in as a non-root user should work. Alternatively, you should be able to log in as the mysql root user that has an empty password if you run the client as Unix root (eg. with sudo).

I did already attempt the dpkg-reconfigure, but that's not useful (You can select the password only when creating a new datadir with empty config, and thus a dpkg-reconfigure does not suffice).

logging in with sudo instead works, but weirdly if then I

ALTER USER 'root'@'localhost' IDENTIFIED BY 'a';

I cannot login as normal user by supplying password `a`, and otoh I can still login by sudo-ing and without providing any mysql password. (I presume that this happens due to something like disabling the ability to change permissions when logging in via sudo... weird that this doesn't explicitly generate an error, though)