Issue After plesk upgrade to 18.0.78, ProFTPD terminating (signal 11)

[theunknownstuntman]

Server operating system version

22.04.5 LTS (Jammy Jellyfish)

Plesk version and microupdate number

Plesk Obsidian 18.0.78.0

Hi all,

yesterday I updated several servers to Plesk Obsidian 18.0.78.0. During this update ProFTPD was updated to version 1.3.9a.

Most of the affected servers are running the same Ubuntu version / Plesk version (see above). Two are running Ubuntu 20.04.6 LTS together with Plesk Obsidian 18.0.78.0 and ProFTPD 1.3.9a.

Today I see, that on all afffected Plesk servers, ProFTPD is crashing. Here is a sample from /var/log/syslog:

May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - -----BEGIN STACK TRACE-----
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [0] /lib/x86_64-linux-gnu/libssl.so.3(SSL_get_session+0x4) [0x7f6a3f11be24]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [1] /lib/x86_64-linux-gnu/libssl.so.3(SSL_get_session+0x4) [0x7f6a3f11be24]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [2] proftpd: 31.14.254.109:7178: AUTH TLS(+0xe2a1f) [0x56233ff06a1f]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [3] proftpd: 31.14.254.109:7178: AUTH TLS(+0xd12bf) [0x56233fef52bf]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [4] proftpd: 31.14.254.109:7178: AUTH TLS(+0xd6315) [0x56233fefa315]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [5] proftpd: 31.14.254.109:7178: AUTH TLS(pr_module_call+0x49) [0x56233fe7ddf9]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [6] proftpd: 31.14.254.109:7178: AUTH TLS(+0x32928) [0x56233fe56928]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [7] proftpd: 31.14.254.109:7178: AUTH TLS(pr_cmd_dispatch_phase+0x47c) [0x56233fe5715c]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [8] proftpd: 31.14.254.109:7178: AUTH TLS(+0x33b65) [0x56233fe57b65]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [9] proftpd: 31.14.254.109:7178: AUTH TLS(+0x3429c) [0x56233fe5829c]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [10] proftpd: 31.14.254.109:7178: AUTH TLS(main+0x788) [0x56233fe4e128]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [11] /lib/x86_64-linux-gnu/libc.so.6(+0x29d90) [0x7f6a3ea88d90]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [12] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80) [0x7f6a3ea88e40]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - [13] proftpd: 31.14.254.109:7178: AUTH TLS(_start+0x25) [0x56233fe4e645]
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - -----END STACK TRACE-----
May 12 21:03:49 xyz proftpd[1139701]: 0.0.0.0 (31.14.254.109[31.14.254.109]) - ProFTPD terminating (signal 11)

ProFTPD can be restarted via "service xinetd restart" successfully, so I assume, that the crashes are triggered by an external event.
As I haven't seen any crashes regarding ProFTPD before, I assume that they might have to do with the Plesk / ProFTPD update.

Has anyone seen similar errors? Is this a bug in ProFTPD or Plesk related? I am grateful for any advice.

 

[alapshin]

Hello @theunknownstuntman !
Just checked with the same configuration:
# proftpd -V
Compile-time Settings:
Version: 1.3.9a (maint)
Platform: LINUX [Linux 5.4.0-216-generic x86_64]
OS/Release:
NAME="Ubuntu"
VERSION="20.04.6 LTS (Focal Fossa)"
. . .
On Plesk Obsidian 18.0.78.0

Nothing similar with your case. I suggest the following:

1. Check if anything suspicious in

• /var/log/plesk/xferlog
• /var/log/plesk/ftp_tls.log

logfiles.

2. Check service itself
systemctl status xinetd

3. Make sure that configuration files are in order:
# proftpd -t

# grep -Rin 'TLS' /etc/proftpd* 2>/dev/null

For deeper investigation "in place" submit a ticket to Plesk support

 

[theunknownstuntman]

@alapshin , thank your for your answer!

Here are my findings:

• /var/log/plesk/xferlog is empty
• /var/log/plesk/ftp_tls.log shows this, when ProFTPD crashed again

2026-05-13 14:02:42,768 mod_tls/2.9.2[231459]: added 1 certs from '/opt/psa/admin/conf/httpsd.pem' to SSL_CTX certificate chain
2026-05-13 14:02:46,075 mod_tls/2.9.2[231462]: added 1 certs from '/opt/psa/admin/conf/httpsd.pem' to SSL_CTX certificate chain
2026-05-13 14:02:46,101 mod_tls/2.9.2[231462]: TLS/TLS-C requested, starting TLS handshake
2026-05-13 14:02:46,126 mod_tls/2.9.2[231462]: unable to accept TLS connection: system call error: [104] Connection reset by peer

xinetd only shows the entries I see in syslog, when ProFTPD crashed.

systemctl status xinetd

● xinetd.service - LSB: Starts or stops the xinetd daemon.
Loaded: loaded (/etc/init.d/xinetd; generated)
Active: active (running) since Wed 2026-05-13 13:17:47 CEST; 1h 14min ago
Docs: man:systemd-sysv-generator(8)
Process: 223452 ExecStart=/etc/init.d/xinetd start (code=exited, status=0/SUCCESS)
Tasks: 1 (limit: 38368)
Memory: 508.0K
CPU: 234ms
CGroup: /system.slice/xinetd.service
└─223462 /usr/sbin/xinetd -pidfile /run/xinetd.pid -stayalive -inetd_compat -inetd_ipv6

May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [6] proftpd: 31.14.254.69:5330: AUTH TLS(+0x32928) [0x55c1729ac928]
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [7] proftpd: 31.14.254.69:5330: AUTH TLS(pr_cmd_dispatch_phase+0x47c) [>
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [8] proftpd: 31.14.254.69:5330: AUTH TLS(+0x33b65) [0x55c1729adb65]
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [9] proftpd: 31.14.254.69:5330: AUTH TLS(+0x3429c) [0x55c1729ae29c]
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [10] proftpd: 31.14.254.69:5330: AUTH TLS(main+0x788) [0x55c1729a4128]
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [11] /lib/x86_64-linux-gnu/libc.so.6(+0x29d90) [0x7fa48843dd90]
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [12] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80) [0x7fa4884>
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - [13] proftpd: 31.14.254.69:5330: AUTH TLS(_start+0x25) [0x55c1729a4645]
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - -----END STACK TRACE-----
May 13 14:02:46 xyz proftpd[231462]: 0.0.0.0 (31.14.254.69[31.14.254.69]) - ProFTPD terminating (signal 11)

Configuration files are fine.

grep -Rin 'TLS' /etc/proftpd* 2>/dev/null

/etc/proftpd.conf:45:<IfModule mod_tls.c>
/etc/proftpd.conf:47: TLSEngine on
/etc/proftpd.conf:48: TLSRequired off
/etc/proftpd.conf:50: TLSLog /var/log/plesk/ftp_tls.log
/etc/proftpd.conf:52: TLSRSACertificateFile /opt/psa/admin/conf/httpsd.pem
/etc/proftpd.conf:53: TLSRSACertificateKeyFile /opt/psa/admin/conf/httpsd.pem
/etc/proftpd.conf:54: TLSCertificateChainFile /opt/psa/admin/conf/httpsd.pem
/etc/proftpd.conf:56: # Authenticate clients that want to use FTP over TLS?
/etc/proftpd.conf:57: TLSVerifyClient off
/etc/proftpd.conf:59: # Allow SSL/TLS renegotiations when the client requests them, but
/etc/proftpd.conf:61: # SSL/TLS renegotiations; when mod_tls forces a renegotiation, these
/etc/proftpd.conf:64: TLSRenegotiate none
/etc/proftpd.conf:66: # As of ProFTPD 1.3.3rc1, mod_tls only accepts SSL/TLS data connections
/etc/proftpd.conf:69: TLSOptions NoSessionReuseRequired
/etc/proftpd.d/ssl.conf:2:<IfModule mod_tls.c>
/etc/proftpd.d/ssl.conf:3:TLSDHParamFile /opt/psa/etc/dhparams2048.pem
/etc/proftpd.d/ssl.conf:7:<IfModule mod_tls.c>
/etc/proftpd.d/ssl.conf:8:TLSProtocol TLSv1.2 TLSv1.3
/etc/proftpd.d/ssl.conf:9:TLSCipherSuite EECDH+AESGCM+AES128:EECDH+AESGCM+AES256:EECDH+CHACHA20:EECDH+SHA256+AES128:EECDH+SHA384+AES256:EECDH+SHA1+AES128:EECDH+SHA1+AES256:EECDH+HIGH:AESGCM+AES128:AESGCM+AES256:CHACHA20:SHA256+AES128:SHA256+AES256:SHA1+AES128:SHA1+AES256:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!3DES:!MD5:!PSK:!KRB5:!aECDH:!kDH:!EDH
/etc/proftpd.d/ssl.conf:10:TLSServerCipherPreference on
/etc/proftpd.d/50-plesk.conf:10:<IfModule mod_tls.c>
/etc/proftpd.d/50-plesk.conf:11: TLSEngine on
/etc/proftpd.d/50-plesk.conf:12: TLSRequired on

 

[alapshin]

Thank yuo for the provided data.
As I see
TLSRequired on in /etc/proftpd.d/50-plesk.conf
This is differ from my test set.

I suggest the following actions for investigation:
1.
in /etc/proftpd.d/50-plesk.conf set TLSRequired off

2.
restart the service service xinetd restart

3.
Check that service is up and running and port 21 is listening by it:
# systemctl status xinetd
# ss -ltnp | grep ':21'
LISTEN 0 64 *:21 *:* users: (("xinetd",pid=6400,fd=5))

4.
from he server with the issue check handshake by:
# openssl s_client -connect 127.0.0.1:21 -starttls ftp
(it is okay if you face "Verification error: self signed certificate")

5.
from the another server
# openssl s_client -connect YOUR_SERVER_IP:21 -starttls ftp
check handshake.

6.
Check logfiles again.

• /var/log/plesk/xferlog
• /var/log/plesk/ftp_tls.log
• /var/log/syslog