Be aware when you’re migrating from MySQL 5.7 to 8.0 on how you’re doing and what kind of applications have access to it. The version 8.0 introduced a new authentication plugin called caching_sha2_password and it’s the default auth plugin now. Here is the list of compatible connectors to check if your app is ok with that or if you should call the dev team.
Example: If, for some reason, you get stuck with the following error (PHP sample), you have to do a few changes.
Connect Error: SQLSTATE[HY000]  The server requested authentication method unknown to the client
Edit your config file and set the option default-authentication-plugin with mysql_native_password value, restart the server and set the password again with the following command.
[mysqld] /... other configs .../ default-authentication-plugin=mysql_native_password
ALTER USER 'adv'@'localhost' IDENTIFIED WITH mysql_native_password BY '1AB@8CD#E91F22!';
New users should be created the same way. Be aware that you have to do that just for users that the application will use. Regular users for DBAs and queries you don’t have to do that change.
So, look out before just doing a update on your server, or you could break your app 😉