After a reboot, Dovecot stopped authenticating users. Since I'm using IMAP authentication for various things, this is a huge problem for me. This is the sort of error I'm getting:
Apr 11 07:09:04 kaitain dovecot: auth-worker(2689): Error: dict(firstname.lastname@example.org,18.104.22.168): Failed to lookup key shared/passdb/%u
Can anyone help? I haven't changed anything, other than restarting the VM.