Wrong message "Check your Internet connection."

[Fabio Marconi]

Hi
everytime it runs it ends showing the box "Failed to download repository information. Check your internet connection". It instead works as expected.
The error probably is here:

Err:7 https://download.docker.com/linux/ubuntu \ Release
  404 Not Found [IP: 108.138.199.73 443]
Reading package lists... Done
E: The repository 'https://download.docker.com/linux/ubuntu \ 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.
njin@Fluid:~$

So it is just a wrong message in that box, screenshot attached

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: update-manager 1:22.04.8
ProcVersionSignature: Ubuntu 5.15.0-23.23-generic 5.15.27
Uname: Linux 5.15.0-23-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu79
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Mar 29 22:04:44 2022
ExecutablePath: /usr/bin/update-manager
GsettingsChanges:
 b'com.ubuntu.update-manager' b'first-run' b'false'
 b'com.ubuntu.update-manager' b'launch-count' b'383'
 b'com.ubuntu.update-manager' b'launch-time' b'int64 1648584138'
 b'com.ubuntu.update-manager' b'show-details' b'true'
 b'com.ubuntu.update-manager' b'window-width' b'645'
InstallationDate: Installed on 2021-04-18 (345 days ago)
InstallationMedia: Ubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
InterpreterPath: /usr/bin/python3.10
PackageArchitecture: all
Python3Details: /usr/bin/python3.10, Python 3.10.3, python3-minimal, 3.10.1-0ubuntu2
PythonDetails: N/A
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)

[Fabio Marconi (fabiomarconi)]

Confirmed by screenshot

[Julian Andres Klode (juliank)]

You have a sources.list file with a line starting

deb https://download.docker.com/linux/ubuntu \

which is wrong - \ is no valid codename. Fix your sources.list.

[Fabio Marconi (fabiomarconi)]

Sorry, perhaps I was not clear.
I know my sources.list.d is wrong but what I mean is that the message "check your internet connection" is wrong because the internet connection is working. Just a graphical issue, I suggest to remove the "Check your internet connection" written.
Thanks and BR

[Julian Andres Klode (juliank)]

Sorry, but checking the internet connection is a useful thing to suggest when updating fails. We can't have special messages for every type of failure.