If you are using Debian, yesterday they released new point versions (12.2 for bookworm and 11.8 for bullseye) and mariadb-server was updated so maybe your error message is because it, just check that it was a one-time error and that mysql is up and running.
Regarding dovecot, as far as I know it has not been updated recently so check you have enough space in your system and check dovecot and systemd logs to know what is going on.