Dovecot version 2.3.17 - mail replication stopped working

[Daniel Botting]

Hi,

We upgraded to Dovecot 2.3.17 today and mail replication has stopped 
working as expected, the error in mail.err is:

Oct 28 10:27:44 hostname dovecot: imap-login: Error: 
net_connect_unix(/var/run/dovecot/stats-writer) failed: No such file or 
directory

Oct 28 10:28:47 hostname dovecot: doveadm: Error: sync: invalid option 
-- 'T'

This is constantly repeated afterwards

All the files in /var/run/dovecot have last modified time of 10:27

The permissions on both hosts for this file are:

srw-rw----  1 root    dovecot    0 Oct 28 10:27 stats-writer=

OS: Debian 10.11

Doveconf -n output below:

# 2.3.17 (e2aa53df5b): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.17 (054dddfa)
# OS: Linux 4.19.0-18-amd64 x86_64 Debian 10.11
# Hostname: mailserver fqdn
auth_verbose = yes
default_vsz_limit = 0
doveadm_password = # hidden, use -P to show it
first_valid_gid = 8
first_valid_uid = 8
last_valid_gid = 8
last_valid_uid = 8
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
mail_gid = 8
mail_location = maildir:~/Maildir
mail_plugins = " notify replication"
mail_uid = 8
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope 
encoded-character vacation subaddress comparator-i;ascii-numeric 
relational regex imap4flags copy include variables body enotify 
environment mailbox date index ihave duplicate mime foreverypart 
extracttext editheader imapflags
namespace inbox {
   inbox = yes
   location =
   mailbox Drafts {
     special_use = \Drafts
   }
   mailbox Junk {
     special_use = \Junk
   }
   mailbox Sent {
     special_use = \Sent
   }
   mailbox "Sent Messages" {
     special_use = \Sent
   }
   mailbox Trash {
     special_use = \Trash
   }
   prefix =
}
passdb {
   args = /etc/dovecot/dovecot-ldap.conf.ext
   driver = ldap
}
plugin {
   mail_replica = tcps:fqdn:port number
   sieve = ~/.dovecot.sieve
   sieve_dir = ~/sieve
   sieve_extensions = +editheader +imapflags
}
postmaster_address = postmaster at ourdomain
protocols = " imap sieve pop3"
replication_dsync_parameters = -d -N -l 15 -U -T 10
replication_max_conns = 24
service aggregator {
   fifo_listener replication-notify-fifo {
     user = mail
   }
   unix_listener replication-notify {
     user = mail
   }
}
service auth {
   unix_listener /var/run/dovecot-exim-bridge {
     mode = 0660
     user = Debian-exim
   }
}
service doveadm {
   inet_listener {
     port = 12345
     ssl = yes
   }
}
service imap-login {
   inet_listener imap {
     port = 143
   }
   inet_listener imaps {
     port = 993
     ssl = yes
   }
   process_limit = 512
   process_min_avail = 4
   service_count = 1
}
service imap {
   process_limit = 1024
}
service managesieve-login {
   inet_listener sieve {
     port = 4190
   }
   process_min_avail = 1
   service_count = 8
   vsz_limit = 256 M
}
service managesieve {
   process_limit = 1024
}
service replicator {
   process_min_avail = 1
   unix_listener replicator-doveadm {
     mode = 0666
   }
}
ssl = required
ssl_cert = </ssl cert path
ssl_cipher_list = ALL:!LOW:!SSLv2:!EXP:!aNULL
ssl_client_ca_dir = /etc/ssl/certs
ssl_key = # hidden, use -P to show it
userdb {
   args = /etc/dovecot/dovecot-ldap.conf.ext
   driver = ldap
   override_fields = home=/var/mail/%u uid=mail gid=mail
}
protocol lda {
   mail_plugins = " notify replication sieve"
}
protocol imap {
   mail_max_userip_connections = 32
   mail_plugins = " notify replication"
}
protocol sieve {
   mail_max_userip_connections = 10
   managesieve_logout_format = bytes=%i/%o
   managesieve_max_line_length = 64 k
}

Best regards

Daniel