Thanks for your help. I really appreciate that! unfortunately, even if I run the same command, I v'e got the following results (even if I have the commercial editon - perpetual licences 25 w) :
apt-key list | grep -i -B3 -A3 'zentyal'
Warning: apt-key output should not be parsed (stdout is not a terminal)
pub rsa4096 2020-10-22 [SC]
DFAC 0C01 657C E14F F733 87CD 19CB DC0A 4E38 9175
uid [ unknown] Zentyal Community Repository <
blorente@zentyal.com>
sub rsa4096 2020-10-22 [E]
sub rsa4096 2020-10-22 [S ]
pub dsa1024 2011-10-03 [SC]
658A 4D9F 8A8F 16B5 8BE6 2DD0 76CB 3C6D 0D64 EFEC
uid [ unknown] Zentyal (Packages Archive) <
it@zentyal.com>
sub elg2048 2011-10-03 [E]
/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-archive.gpg
uid [ unknown] Zabbix LLC <
packager@zabbix.com>
sub rsa2048 2016-07-15 [E]
/etc/apt/trusted.gpg.d/zentyal-qa.asc
-------------------------------------
pub rsa2048 2012-09-07 [SC]
FFFF 8A63 82DC 816C 277B 935E 8E92 29F7 E23F 4777
uid [ unknown] Zentyal Release Team <
release-team@zentyal.org>
sub rsa2048 2012-09-07 [E]
and for the command : sudo apt-get update
[sudo] password for valery:
Hit:1
http://ch.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2
http://ch.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:3
http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:4
http://ch.archive.ubuntu.com/ubuntu bionic-backports InRelease
Hit:6
https://download.mono-project.com/repo/ubuntu stable-bionic InRelease
Get:5
http://packages.zentyal.com/zentyal-qa 6.2 InRelease [7,484 B]
Hit:7
http://repo.zabbix.com/zabbix/5.0/ubuntu bionic InRelease
Hit:8
https://cpkg.datto.com/datto-deb/public/bionic bionic InRelease
Err:5
http://packages.zentyal.com/zentyal-qa 6.2 InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY EF358ACFF842CD9E
Hit:9
https://packagecloud.io/ookla/speedtest-cli/ubuntu bionic InRelease
Reading package lists... Done
W: Target Packages (main/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Packages (main/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Translations (main/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: GPG error:
http://packages.zentyal.com/zentyal-qa 6.2 InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY EF358ACFF842CD9E
E: The repository '
http://packages.zentyal.com/zentyal-qa 6.2 InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(
manpage for repository creation and user configuration details.
W: Target Packages (main/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Packages (main/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Translations (main/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1
W: Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list.d/mono-official-stable.list:1 and /etc/apt/sources.list.d/mono-stable.list:1