Hi,
I have some problems of segfault at doveconf:
Jul 
2 08:13:16 mail kernel: [1415540.297823] doveconf[7103]:
segfault at 560cb801e000 ip 00007f861da742d0 sp 00007ffe2d671548 error 6 in libc-2.23.so[7f861d9e5000+1c0000]
Jul 
2 15:45:38 mail kernel: [1442682.919193] doveconf[11915]:
segfault at 563b32420000 ip 00007fcb127ae2d0 sp 00007ffecfc7b598 error 6 in libc-2.23.so[7fcb1271f000+1c0000]
Jul 
2 20:27:37 mail kernel: [1459601.781407] doveconf[14680]:
segfault at 55618f01b000 ip 00007f44137202d0 sp 00007ffcbb8d8628 error 6 in libc-2.23.so[7f4413691000+1c0000]
Jul 
2 21:35:36 mail kernel: [1463680.435538] doveconf[15090]:
segfault at 55ea7521d000 ip 00007f0bfe79f2d0 sp 00007ffd272793b8 error 6 in libc-2.23.so[7f0bfe710000+1c0000]
Jul 
3 00:44:28 mail kernel: [1475013.132492] doveconf[16253]:
segfault at 561feea20000 ip 00007f34be2be2d0 sp 00007ffe731ef4b8 error 6 in libc-2.23.so[7f34be22f000+1c0000]
System configuration follows:
lsb_release -d
Description:  
Ubuntu 16.04.6 LTS
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 16.04.6 LTS 
disable_plaintext_auth = no
first_valid_gid = 8
first_valid_uid = 150
last_valid_gid = 8
last_valid_uid = 150
mail_location = mbox:~/mail:INBOX=/var/mail/%u
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
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 = INBOX.
}
passdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
plugin {
  quota_warning = storage=95%% quota-warning 95 %u
  quota_warning2 = storage=80%% quota-warning 80 %u
  sieve = /var/vmail/%d/%u/.dovecot.sieve
  sieve_dir = /var/vmail/%d/%u/sieve
  sieve_global_dir = /var/lib/dovecot/sieve/
  sieve_storage = /var/vmail/%d/%u/sieve
}
protocols = " imap sieve pop3"
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  unix_listener auth-userdb {
    group = mail
    mode = 0600
    user = vmail
  }
}
service quota-warning {
  executable = script /usr/bin/quota-warning.sh
  unix_listener quota-warning {
    user = vmail
  }
  user = dovecot
}
ssl_ca = </etc/ssl/certs/SecureTrust_CA_mauri2.pem
ssl_cert = </etc/ssl/certs/dovecot6.pem
ssl_cipher_list = TLSv1+HIGH:!SSLv2:!RC4:!aNULL:!eNULL:!3DES:!IDEA:!SEED
ssl_key = </etc/ssl/private/dovecot3.pem
ssl_prefer_server_ciphers = yes
userdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
protocol lda {
  mail_plugins = " sieve"
}
protocol pop3 {
  pop3_uidl_format = %Mf
}
dovecot --version
2.2.22 (fe789d2)
apt-get update
Hit:1 http://ubuntu.seeweb.it/ubuntu xenial InRelease
Hit:2 http://ubuntu.seeweb.it/ubuntu xenial-updates InRelease
Hit:3 http://ubuntu.seeweb.it/ubuntu xenial-backports InRelease
Get:4 http://ubuntu.seeweb.it/ubuntu-security xenial-security InRelease [109 kB]
Fetched 109 kB in 1s (99.1 kB/s)
                       
Reading package lists... Done
apt-get upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
apt-get dist-upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Any hint about it ? Sometimes, from my webmail I receive an error communicating with server, but no other errors.
Cordially,
Claudio Prono.
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