Password mismatch after upgrade to Ubuntu Focal

[Jeffrey van Doesburg]

Hi!

Today I upgraded one of our Dovecot servers from Ubuntu 18.04 to Ubuntu
20.04. After the upgrade I have login issues because the password
didn't match.

I also installed Dovecot on a clean Ubuntu 20.04 server with the same
configuration files. And here I also got the password match issue.

We're using LDAP for managing the login credentials and I'm 100% sure
the password is correct. With the debug options on, you will see
something like this:

CRYPT(<PLAIN_TEXT_PASSWORD>) != '$6$<SECRET_PASSWORD_HASH>'

Does somebody know if there are know issues with Dovecot 2.3.7.2-
1ubuntu3.1 on Ubuntu 20.04 and with the LDAP driver?

dovecot -n
-------------------------
# 2.3.7.2 (3c910f64b): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.7.2 ()
# OS: Linux 5.4.0-33-generic x86_64 Ubuntu 20.04 LTS ceph
# Hostname: server.example.tld
auth_verbose = yes
disable_plaintext_auth = no
listen = *, [::]
log_timestamp = "%Y-%m-%d %H:%M:%S "
login_greeting = POP/IMAP Service ready.
mail_fsync = always
mail_location = maildir:/mail/%u
mail_privileged_group = mail
passdb {
  args = /etc/dovecot/dovecot-ldap.conf
  driver = ldap
}
plugin {
  acl = vfile:/etc/dovecot/acls/:cache_secs=30
  autosubscribe = Trash
  autosubscribe2 = Sent
  autosubscribe3 = Drafts
}
protocols = imap pop3
service auth {
  user = root
}
service imap-create-folder {
  executable = script-login /usr/local/sbin/dovecot-create-dirs.sh
}
service imap-login {
  process_min_avail = 15
  service_count = 0
}
service imap {
  executable = imap imap-create-folder
}
service pop3-login {
  process_min_avail = 15
  service_count = 0
}
service pop3 {
  drop_priv_before_exec = yes
}
ssl = no
userdb {
  driver = prefetch
}
protocol imap {
  mail_max_userip_connections = 25
  mail_plugins = acl
}
protocol pop3 {
  pop3_uidl_format = %f
}
------------------------------

/etc/dovecot/dovecot-ldap.conf
------------------------------
hosts = ldap.server.example.tld

dn = <XXXXX>
dnpass = <XXXXX>
auth_bind = no
ldap_version = 3
base = <XXXXX>

pass_attrs = <XXXXX>
pass_filter = <XXXXX>
-----------------

Thanks!

Jeffrey