Sorry to unearth this old topic,
I did as per the instructions and got :
root@stationeri:~# wget -O - http://[redacted]@download.egroupware.org/repos/community/Debian_9.0/Release.key |apt-key add -
--2020-06-02 15:09:46-- http://[redacted]@download.egroupware.org/repos/community/Debian_9.0/Release.key
Resolving download.egroupware.org (download.egroupware.org)... 185.48.117.239
Connecting to download.egroupware.org (download.egroupware.org)|185.48.117.239|:80... connected.
HTTP request sent, awaiting response... 401 Unauthorized
Authentication selected: Basic realm="EGroupware Community repo"
Reusing existing connection to download.egroupware.org:80.
HTTP request sent, awaiting response... 200 OK
Length: 1662 (1.6K) [application/pgp-keys]
Saving to: ‘STDOUT’
- 100%[========================================================================================================================================>] 1.62K --.-KB/s in 0.001s
2020-06-02 15:09:47 (1.31 MB/s) - written to stdout [1662/1662]
gpg: invalid key resource URL '/tmp/apt-key-gpghome.3bTipoQgtU/server:eGroupWare.asc.gpg'
gpg: keyblock resource '(null)': General error
gpg: key DC30D7C23CBBABEE: 4 signatures not checked due to missing keys
gpg: key 4DFAB270CAA96DFA: 4 signatures not checked due to missing keys
gpg: key DCC9EFBF77E11517: 2 signatures not checked due to missing keys
gpg: key 7638D0442B90D010: 4 signatures not checked due to missing keys
gpg: key 9D6D8F6BC857C906: 4 signatures not checked due to missing keys
gpg: key CBF8D6FD518E17E1: 2 signatures not checked due to missing keys
gpg: key E0B11894F66AEC98: 5 signatures not checked due to missing keys
gpg: key EDA0D2388AE22BA9: 5 signatures not checked due to missing keys
gpg: key EF0F382A1A7B6500: 2 signatures not checked due to missing keys
gpg: key 3545DFD68B5C64E0: 1 signature not checked due to a missing key
gpg: Total number processed: 11
gpg: skipped new keys: 11
(if I mod the wget line to download it instead, it seems to be fine:
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v2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=wsDh
-----END PGP PUBLIC KEY BLOCK-----
From there, it was only downhill:
root@stationeri:~# apt update
Hit:1 http://download.opensuse.org/repositories/server:/eGroupWare/Debian_10 InRelease
Ign:2 http://download.egroupware.org/repos/community/Debian_9.0 ./ InRelease
Hit:3 http://security.debian.org/debian-security buster/updates InRelease
Hit:4 http://deb.debian.org/debian buster InRelease
Get:5 http://download.egroupware.org/repos/community/Debian_9.0 ./ Release [995 B]
Hit:6 http://deb.debian.org/debian buster-updates InRelease
Hit:7 http://deb.debian.org/debian buster-backports InRelease
Get:8 http://download.egroupware.org/repos/community/Debian_9.0 ./ Release.gpg [827 B]
Ign:8 http://download.egroupware.org/repos/community/Debian_9.0 ./ Release.gpg
Reading package lists... Done
W: GPG error: http://download.egroupware.org/repos/community/Debian_9.0 ./ Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 511F0710BB2A8E02
E: The repository 'http://download.egroupware.org/repos/community/Debian_9.0 ./ Release' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
N: Usage of apt_auth.conf(5) should be preferred over embedding login information directly in the sources.list(5) entry for 'http://download.egroupware.org/repos/community/Debian_9.0'
and the egroupware-epl-groups package is not there:
root@stationeri:~# apt install egroupware-epl [tab][tab]
egroupware-epl egroupware-epl-compat egroupware-epl-importexport egroupware-epl-news-admin egroupware-epl-projectmanager egroupware-epl-sitemgr egroupware-epl-wiki
egroupware-epl-bookmarks egroupware-epl-core egroupware-epl-infolog egroupware-epl-notifications egroupware-epl-registration egroupware-epl-timesheet
egroupware-epl-calendar egroupware-epl-esync egroupware-epl-jdots egroupware-epl-phpbrain egroupware-epl-resources egroupware-epl-tracker
egroupware-epl-collabora egroupware-epl-filemanager egroupware-epl-mail egroupware-epl-phpfreechat egroupware-epl-sambaadmin egroupware-epl-vendor
root@stationeri:~# apt install egroupware-epl-
Luckily, manual download with wget and install worked :
root@stationeri:~# dpkg -i egroupware-epl-groups_17.1.20180412_all.deb
Selecting previously unselected package egroupware-epl-groups.
(Reading database ... 49402 files and directories currently installed.)
Preparing to unpack egroupware-epl-groups_17.1.20180412_all.deb ...
Unpacking egroupware-epl-groups (17.1.20180412) ...
Setting up egroupware-epl-groups (17.1.20180412) ...
egroupware
Waiting for egroupware container to restart ...
EGroupware successful updated
Any idea why this happened? My Debian 10 is with the buster-backports repo
root@stationeri:~# apt list |grep gnupg
gnupg-agent/stable 2.2.12-1+deb10u1 all
gnupg-l10n/buster-backports,now 2.2.20-1~bpo10+1 all [installed,automatic]
gnupg-pkcs11-scd-proxy/stable 0.9.2-1 amd64
gnupg-pkcs11-scd/stable 0.9.2-1 amd64
gnupg-utils/buster-backports,now 2.2.20-1~bpo10+1 amd64 [installed,automatic]
gnupg1-l10n/stable 1.4.23-1 all
gnupg1/stable 1.4.23-1 amd64
gnupg2/stable 2.2.12-1+deb10u1 all
gnupg/buster-backports,now 2.2.20-1~bpo10+1 all [installed]
Thanks in adv.
el_es