Why won't Dovecot start?

Question

linux

Hello. For some reason, Dovecot does not start.
Attempts to manually start it do not lead to anything (as I understand it, because if you start the service and then try to restart it, the stop: Uknown instance line appears )

/etc/dovecot/conf.d/10-master.conf

#default_process_limit = 100
#default_client_limit = 1000
# Default VSZ (virtual memory size) limit for service processes. This is mainly
# intended to catch and kill processes that leak memory before they eat up
# everything.
#default_vsz_limit = 256M
# Login user is internally used by login processes. This is the most untrusted
# user in Dovecot system. It shouldn't have access to anything at all.
#default_login_user = dovenull
# Internal user is used by unprivileged processes. It should be separate from
# login user, so that login processes can't disturb other processes.
#default_internal_user = dovecot
service imap-login {
inet_listener imap {
port = 0
}
inet_listener imaps {
#port = 993
#ssl = yes
}
# Number of connections to handle before starting a new process. Typically
# the only useful values are 0 (unlimited) or 1. 1 is more secure, but 0
# is faster.
#service_count = 1
# Number of processes to always keep waiting for more connections.
#process_min_avail = 0
# If you set service_count=0, you probably need to grow this.
#vsz_limit = 64M
}
service pop3-login {
inet_listener pop3 {
port = 0
}
inet_listener pop3s {
#port = 995
#ssl = yes
}
}
service lmtp {
unix_listener /var/spool/postfix/private/dovecot-lmtp {
mode = 0600
user = postfix
group = postfix
}
# Create inet listener only if you can't use the above UNIX socket
#inet_listener lmtp {
# Avoid making LMTP visible for the entire internet
#address =
#port =
#}
}
service imap {
# Most of the memory goes to mmap()ing files. You may need to increase this
# limit if you have huge mailboxes.
#vsz_limit = 256M
# Max. number of IMAP processes (connections)
#process_limit = 1024
}
service pop3 {
# Max. number of POP3 processes (connections)
#process_limit = 1024
}
service auth {
unix_listener /var/spool/postfix/private/auth {
mode = 0666
user = postfix
group = postfix
}
unix_listener auth-userdb {
mode = 0600
user = vmail
#group =
}
# Postfix smtp-auth
#unix_listener /var/spool/postfix/private/auth {
# mode = 0666
#}
# Auth process is run as this user.
user = dovecot
}
service auth-worker {
user = vmail
}
service dict {
# If dict proxy is used, mail processes should have access to its socket.
# For example: mode=0660, group=vmail and global mail_access_groups=vmail
unix_listener dict {
#mode = 0600
#user =
#group =
}
}

doveconf -n

[email protected]:~# doveconf -n
# 2.2.22 (fe789d2): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.13 (7b14904)
# OS: Linux 4.4.0-45-generic x86_64 Ubuntu 16.04.2 LTS 
auth_mechanisms = plain login digest-md5 cram-md5
auth_username_format = %u
mail_location = maildir:/var/mail/vhosts/%d/%n
mail_privileged_group = mail
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-sql.conf.ext
  driver = sql
}
protocols = imap pop3 lmtp
service auth-worker {
  user = vmail
}
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0666
    user = postfix
  }
  unix_listener auth-userdb {
    mode = 0600
    user = vmail
  }
  user = dovecot
}
service imap-login {
  inet_listener imap {
    port = 0
  }
}
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
}
service pop3-login {
  inet_listener pop3 {
    port = 0
  }
}
ssl_cert = </etc/ssl/mail.yubex.ru.crt
ssl_key = </etc/ssl/mail.yubex.ru.crt
userdb {
  args = uid=vmail gid=vmail home=/var/mail/vhosts/%d/%n
  driver = static
}

[email protected]:~# sudo service dovecot start
dovecot start/running, process 8741
[email protected]:~# sudo service dovecot restart
stop: Unknown instance: 
dovecot start/running, process 8805

And the Postfix logs also show that it is not possible to connect to Dovecot

spoiler

Jul 29 12:57:41 vm-69283c2b postfix/smtpd[8329]: warning: SASL: Connect to private/auth failed: Connection refused
Jul 29 12:57:41 vm-69283c2b postfix/smtpd[8329]: fatal: no SASL authentication mechanisms
Jul 29 12:57:42 vm-69283c2b postfix/master[8326]: warning: process /usr/lib/postfix/sbin/smtpd pid 8329 exit status 1
Jul 29 12:57:42 vm-69283c2b postfix/master[8326]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling

Answer 1

Problem solved.
It was necessary to install additional packages dovecot-imapd dovecot-pop3d and dovecot-lmtpd

Answer 2

ok, you showed the postfix logs. And the dovecot logs?