MySQL started, said TLS was fine, and two lines above that, warned me Failed to validate certificate … because invalid CA certificate. It carries on regardless, so the warning is easy to miss, and clients that check the certificate will be the ones to fail.
The password was right, and I still got ERROR 1045 (28000): Access denied. MySQL gives no hint of the real reason: this account has REQUIRE SSL, and the connection didn't use TLS. It caught me over a local socket too, which require_secure_transport would have allowed.
The client was disconnected by the server because of inactivity means this session was idle for longer than MySQL allows, and the server closed it. The mysql client then reconnects by itself, so it looks odd but costs you one retry. Anything that session set up is gone, though.
ERROR 3888: Failed to set up SSL with Unable to get private key means MySQL couldn't use the files you asked it to load. The good news is in the manual: a failed reload changes nothing, and the old certificate keeps running until you fix it.
Connections using insecure transport are prohibited while --require_secure_transport=ON means the server refuses anything unencrypted, and this connection is. Turn TLS on in the client: it's usually one option.
Access denied for user 'inventory_app'@'localhost'. Account is locked. is unusually clear: the password isn't the problem, the account is switched off. One thing I didn't expect: sessions that were already connected kept working.
Authentication requires secure connection comes from how MySQL's default sign-in works: the first time it checks a password, it needs an encrypted connection to do it safely. Connecting over TCP with TLS turned off gets you this error, and the same command worked a minute later, which threw me at first.
Your password does not satisfy the current policy requirements means the validate_password component is on, and it doesn't like this password. The message doesn't say why, but the rules are one query away.
User 'inventory_app' has exceeded the 'max_user_connections' resource (current value: 2) means that one account has as many connections open as it's allowed. The number is in the message, so the question is who has them, and whether the limit is right.
ERROR 1142 (42000): DROP command denied to user means the account you're signed in with doesn't have that right on that table. If the account belongs to an app, that's often exactly what you want. And TRUNCATE gives the same message, which surprised me.
