Ubuntu – I can’t install Python – “Conflicting values set for option Trusted”

aptpackage-managementpythonpython3upgrade

Results of python ––version :

Command 'python' not found, but can be installed with:
    
    sudo apt install python3       
    sudo apt install python        
    sudo apt install python-minimal

You also have python3 installed, you can run 'python3' instead.

Results of cat /etc/apt/sources.list :

# deb cdrom:[Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725)]/ bionic main restricted

# See http://help.ubuntu.com/community http://packages.ros.org/ros/ubuntu/y/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb [trusted=yes] http://br.archive.ubuntu.com/ubuntu/ bionic restricted main
# deb-src http://br.archive.ubuntu.com/ubuntu/ bionic main restricted

## Major bug fix updates produced after the final release of the
## distribution.
# deb-src http://br.archive.ubuntu.com/ubuntu/ bionic-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://br.archive.ubuntu.com/ubuntu/ bionic universe
# deb-src http://br.archive.ubuntu.com/ubuntu/ bionic universe
# deb-src http://br.archive.ubuntu.com/ubuntu/ bionic-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://br.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://br.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://br.archive.ubuntu.com/ubuntu/ bionic-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://br.archive.ubuntu.com/ubuntu/ bionic-backports restricted universe multiverse main
# deb-src http://br.archive.ubuntu.com/ubuntu/ bionic-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 bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner

deb http://security.ubuntu.com/ubuntu bionic-security restricted main
# deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://security.ubuntu.com/ubuntu bionic-security universe
# deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse
deb http://archive.canonical.com/ bionic partner
# deb-src http://archive.canonical.com/ bionic partner
# deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse
deb http://br.archive.ubuntu.com/ubuntu/ bionic-updates main multiverse universe restricted
deb http://my-private-server.test bionic main
# deb-src http://my-private-server.test bionic main  

Results of sudo apt update :

E: Conflicting values set for option Trusted regarding source http://br.archive.ubuntu.com/ubuntu/ bionic
E: The list of sources cannot be read.

Results of /etc/apt/sources.list :

bash: /etc/apt/sources.list: Permission denied

Update

After trying to fix the issue (@PMF please add here what you did), it still does not work. Line 5 of sources.list now reads:

~$ sed -n 5p /etc/apt/sources.list
deb deb [arch=amd64 trusted=yes] http://br.archive.ubuntu.com/ubuntu/ bionic main  http://br.archive.ubuntu.com/ubuntu/ bionic restricted main

Best Answer

You have [trusted=yes] as option in this line:

deb [trusted=yes] http://br.archive.ubuntu.com/ubuntu/ bionic restricted main

but not for the other lines with the same URL, that is why it says that you have conflicting options.

To fix, either add that option to all other lines with the same URL or easier just remove that using the editor of your choice or simply run:

sudo sed -i '/bionic restricted main$/s/^deb \[trusted=yes]/deb/' /etc/apt/sources.list