after upgrade to version 2.3.18, we enconter a lot of errors, such as:

Mar 22 14:08:32 mail2 dovecot: pop3(user@domain)<52269><3y3GeM3aQ+tWadtM>: Panic: file lib-event.c: line 585 (event_reason_code_prefix): assertion failed: (name[0] != '\0')
Mar 22 14:08:32 mail2 dovecot: pop3(user@domain)<52269><3y3GeM3aQ+tWadtM>: Error: Raw backtrace: /usr/lib/dovecot/libdovecot.so.0(backtrace_append+0x42) [0x7f7ce322e012] ->
/usr/lib/dovecot/libdovecot.so.0(backtrace_get+0x1e) [0x7f7ce322e12e] -> /usr/lib/dovecot/libdovecot.so.0(+0x101d4b) [0x7f7ce323ad4b] ->
/usr/lib/dovecot/libdovecot.so.0(+0x101de1) [0x7f7ce323ade1] -> /usr/lib/dovecot/libdovecot.so.0(+0x55519) [0x7f7ce318e519] ->
/usr/lib/dovecot/libdovecot.so.0(+0x594e2) [0x7f7ce31924e2] -> dovecot/pop3(client_handle_input+0x1c9) [0x55d5b5efa539] ->
/usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x69) [0x7f7ce3250f79] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0x96) [0x7f7ce3251066] ->
/usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x40) [0x7f7ce32511e0] -> /usr/lib/dovecot/libdovecot.so.0(master_service_run+0x13) [0x7f7ce31c4003] -> dovecot/pop3(main+0x2e6) [0x55d5b5ef81f6] ->
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xea) [0x7f7ce2f93d0a] -> dovecot/pop3(_start+0x2a) [0x55d5b5ef838a]
Mar 22 14:08:32 mail2 dovecot: pop3(user@domain)<52269><3y3GeM3aQ+tWadtM>: Fatal: master: service(pop3): child 52269 killed with signal 6 (core dumps disabled - https://dovecot.org/bugreport.html#coredumps)



# dovecot -n
# 2.3.18 (9dd8408c18): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.18 (0bc28b32)
# OS: Linux 5.10.0-12-amd64 x86_64 Debian 11.2
# Hostname:
auth_cache_verify_password_with_worker = yes
auth_failure_delay = 5 secs
auth_mechanisms = plain login
auth_verbose = yes
auth_worker_max_count = 256
default_client_limit = 10000
default_process_limit = 10000
default_vsz_limit = 1 G
dict {
  lastlogin = mysql:/etc/dovecot/mysql/dovecot-dict-lastlogin.conf
  quotadict = mysql:/etc/dovecot/mysql/dovecot-dict-quota.conf
}
disable_plaintext_auth = no
first_valid_uid = 100
imap_hibernate_timeout = 5 secs
imap_idle_notify_interval = 3 mins
log_timestamp = "%Y-%m-%d %H:%M:%S "
login_log_format_elements = user=<%u> method=%m rip=%r lip=%l pid=%p %c
login_trusted_networks =
mail_fsync = always
mail_gid = 8
mail_home = /home/virtual0/%d/%n
mail_location = maildir:~/Maildir
mail_nfs_index = yes
mail_nfs_storage = yes
mail_plugins = zlib quota mail_log notify
mail_privileged_group = mail
mail_uid = 150
maildir_stat_dirs = yes
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 ihave
metric imap_command {
  filter = event=imap_command_finished AND tagged_reply_state=OK
  group_by = cmd_name
}
metric imap_select_no {
  filter = event=imap_command_finished AND cmd_name=SELECT AND tagged_reply_state=NO
}
metric imap_select_no_notfound {
  filter = event=imap_command_finished AND cmd_name=SELECT AND tagged_reply="NO*Mailbox doesn't exist:*"
}
metric storage_http_gets {
  filter = event=http_request_finished AND category=storage AND method=get
}
mmap_disable = yes
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    auto = subscribe
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Spam {
    auto = subscribe
    autoexpunge = 30 days
    special_use = \Junk
  }
  mailbox Trash {
    auto = subscribe
    autoexpunge = 60 days
    special_use = \Trash
  }
  mailbox virtual/All {
    special_use = \All
  }
  prefix =
}
passdb {
  args = /etc/dovecot/mysql/dovecot-sql.conf
  driver = sql
}
plugin {
  last_login_dict = proxy::lastlogin
  last_login_key = # hidden, use -P to show it
  mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
  mail_log_fields = uid box msgid size
  quota = dict:user::proxy::quotadict
  quota_rule2 = Trash:ignore
  quota_rule3 = Spam:ignore
  quota_status_nouser = DUNNO
  quota_status_overquota = 552 5.2.2 The email account that you tried to reach is over quota
  quota_status_success = DUNNO
  quota_warning = storage=95%% quota-warning 95 %u
  quota_warning2 = storage=80%% quota-warning 80 %u
  sieve = ~/.dovecot.sieve
  sieve_before = /etc/dovecot/sieve/default.sieve
  sieve_dir = ~/sieve
  trash = /etc/dovecot/dovecot-trash.conf
  zlib_save = gz
  zlib_save_level = 6
}
protocols = imap sieve pop3 lmtp
service anvil {
  client_limit = 50000
  unix_listener anvil-auth-penalty {
    mode = 00
  }
}
service auth {
  client_limit = 50000
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  unix_listener auth-master {
    group = mail
    mode = 0660
    user = vmail
  }
  user = root
  vsz_limit = 1 G
}
service dict {
  unix_listener dict {
    mode = 0660
    user = vmail
  }
}
service imap-hibernate {
  unix_listener imap-hibernate {
    group = $default_internal_group
    mode = 0660
  }
}
service imap-login {
  inet_listener imap {
    address = *
    port = 143
  }
  inet_listener imaps {
    address = *
    port = 993
  }
  process_min_avail = 16
  service_count = 1
}
service imap {
  extra_groups = $default_internal_group
  process_min_avail = 16
  unix_listener imap-master {
    user = $default_internal_user
  }
  vsz_limit = 2 G
}
service lmtp {
  process_min_avail = 16
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
  vsz_limit = 1 G
}
service managesieve-login {
  inet_listener sieve {
    port = 4190
  }
  process_min_avail = 16
  service_count = 1
}
service managesieve {
  vsz_limit = 1 G
}
service pop3-login {
  inet_listener pop3 {
    address = *
    port = 110
  }
  inet_listener pop3s {
    address = *
    port = 995
  }
  process_min_avail = 16
  service_count = 1
}
service pop3 {
  process_min_avail = 16
  vsz_limit = 1 G
}
service quota-status {
  executable = /usr/lib/dovecot/quota-status -p postfix
  process_min_avail = 16
  unix_listener /var/spool/postfix/private/quota-status {
    group = postfix
    mode = 0666
    user = postfix
  }
}
service quota-warning {
  executable = script /usr/local/bin/quota-warning.sh
  unix_listener quota-warning {
    mode = 0660
    user = vmail
  }
  user = vmail
}
service stats {
  unix_listener stats-reader {
    mode = 0660
    user = vmail
  }
  unix_listener stats-writer {
    mode = 0666
    user = vmail
  }
}
ssl_cert = </etc/dovecot/ssl/domain.pem
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
ssl_min_protocol = TLSv1
userdb {
  args = /etc/dovecot/mysql/dovecot-sql.conf
  driver = sql
}
protocol imap {
  imap_max_line_length = 64 k
  mail_max_userip_connections = 16
  mail_plugins = zlib quota mail_log notify trash imap_quota last_login
}
protocol pop3 {
  mail_max_userip_connections = 10
  mail_plugins = zlib quota mail_log notify last_login
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
  pop3_fast_size_lookups = yes
  pop3_no_flag_updates = yes
  pop3_uidl_format = %08Xu%08Xv
}
protocol sieve {
  mail_max_userip_connections = 10
  managesieve_max_compile_errors = 5
}
protocol lda {
  auth_socket_path = /var/run/dovecot/auth-master
  mail_plugins = zlib quota mail_log notify sieve
  sendmail_path = /usr/lib/sendmail
  syslog_facility = mail
}
protocol lmtp {
  mail_plugins = zlib quota mail_log notify sieve
  syslog_facility = mail
Aurel