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I'm following the instructions at the docker docs for installing on ubuntu 20.04 from repository. I've done this sort of thing for company repositories before, but I've never had it not work like this. These are the commands I run and it recommends:

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

This executes without error, and appears to create the file in the path shown in the command. I then run:

echo \
  "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

This also appears to create the expected string, in the excepted file. When I cat /etc/apt/sources.list.d/docker.list I get:

deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu   focal stable

which I believe is expected. There are no line-breaks. I then run sudo apt update, which is the next step in the procedure, and it returns the following error:

E: Conflicting values set for option Signed-By regarding source https://download.docker.com/linux/ubuntu/ focal: /usr/share/keyrings/docker-archive-keyring.gpg != 
E: The list of sources could not be read.

Thus, I believe that there's something misconfigured with their setup somehow. I don't see how there could be conflicting values for this unless that curl command brought down the wrong key, but I also don't know the inner workings of apt that well. If it's something on my end that I could more or less easily fix, that would be great news.

EDIT here are the contents of /etc/apt/sources.list on my system:

# deb cdrom:[Kubuntu 20.04 LTS _Focal Fossa_ - Release amd64 (20200423)]/ focal main multiverse restricted universe

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ focal main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ focal main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ focal-updates main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ focal-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ focal universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ focal universe
deb http://us.archive.ubuntu.com/ubuntu/ focal-updates universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ focal-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ focal multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ focal multiverse
deb http://us.archive.ubuntu.com/ubuntu/ focal-updates multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ focal-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu focal partner
# deb-src http://archive.canonical.com/ubuntu focal partner

deb http://security.ubuntu.com/ubuntu focal-security main restricted
# deb-src http://security.ubuntu.com/ubuntu focal-security main restricted
deb http://security.ubuntu.com/ubuntu focal-security universe
# deb-src http://security.ubuntu.com/ubuntu focal-security universe
deb http://security.ubuntu.com/ubuntu focal-security multiverse
# deb-src http://security.ubuntu.com/ubuntu focal-security multiverse

# This system was installed using small removable media
# (e.g. netinst, live or single CD). The matching "deb cdrom"
# entries were disabled at the end of the installation process.
# For information about how to configure apt package sources,
# see the sources.list(5) manual.
# deb http://repo.kfocus.org/ubuntu focal main
# deb-src http://repo.kfocus.org/ubuntu focal main
1
  • Please post the contents of your /etc/apt/sources.list. Apr 28, 2021 at 18:07

2 Answers 2

2

I was able to get apt working again after removing this file: /etc/apt/sources.list.d/docker.list

1
  • I was also able to get apt unstuck by removing this file. My issue is that this didn't allow me to perform an install of docker that will track their web source, which is what I was hoping someone here could help me fix.
    – LGS
    Apr 30, 2021 at 4:21
1

In my case, I found another file under /etc/apt/sources.list.d called focal_docker.list which had the exact same content but without the signed-by=/usr/share/keyrings/docker-archive-keyring.gpg part so causing this conflict. I removed this file and everything worked fine afterwards.

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