I was working on installing Docker in the Ubuntu OS of my Dual Boot computer. I entered all of the code in the “1. Set up Docker’s apt repository.” section at https://docs.docker.com/engine/install/ubuntu/#install-using-the-repository in terminal. However after entering “sudo apt-get update” in terminal as shown in the last line in the “1. Set up Docker’s apt repository.” section I get the following errors:

E: Malformed entry 1 in list file /etc/apt/sources.list.d/docker.list (Suite)
E: The list of sources could not be read.

Kindly advise on the way to resolve this issue. My current Ubuntu version is 23.04

I have resolved the issue above by entering:

sudo rm /etc/apt/sources.list.d/docker.list

However, after entering “sudo apt update”, the following gets displayed along with the errors:

Get:1 https://download.docker.com/linux/ubuntu lunar InRelease [48.8 kB]
Hit:2 https://packages.microsoft.com/repos/vscode stable InRelease             
Hit:3 http://archive.ubuntu.com/ubuntu lunar InRelease                         
Hit:4 https://packages.microsoft.com/repos/code stable InRelease               
Hit:5 https://dl.google.com/linux/chrome/deb stable InRelease                  
Hit:6 http://archive.ubuntu.com/ubuntu lunar-updates InRelease      
Ign:7 http://packages.ros.org/ros2/ubuntu lunar InRelease
Hit:8 http://archive.ubuntu.com/ubuntu lunar-backports InRelease
Err:9 http://packages.ros.org/ros2/ubuntu lunar Release
404  Not Found [IP: 2605:bc80:3010::134 80]
Hit:10 http://archive.ubuntu.com/ubuntu lunar-security InRelease
Reading package lists... Done
W: https://download.docker.com/linux/ubuntu/dists/lunar/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
E: The repository 'http://packages.ros.org/ros2/ubuntu lunar Release' does not have a Release file.
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.

Kindly advise on the way to solve this issue