Software & Updates does not currently work in 24.04

[XA Hydra]

Unable to run "Software & Updates" from either the app menu nor Synaptic via Settings -> Repositories. The following error is generated:

Traceback (most recent call last):
  File "/usr/bin/software-properties-gtk", line 100, in <module>
    app = SoftwarePropertiesGtk(datadir=options.data_dir, options=options, file=file)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 163, in __init__
    SoftwareProperties.__init__(self, options=options, datadir=datadir,
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 109, in __init__
    self.backup_sourceslist()
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 437, in backup_sourceslist
    source_bkp = SourceEntry(line=source.line,file=source.file)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/aptsources/sourceslist.py", line 509, in __init__
    raise ValueError("Classic SourceEntry cannot be written to .sources file")
ValueError: Classic SourceEntry cannot be written to .sources file

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: software-properties-gtk 0.99.42
ProcVersionSignature: Ubuntu 6.8.0-11.11-generic 6.8.0-rc4
Uname: Linux 6.8.0-11-generic x86_64
ApportVersion: 2.28.0-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Mar 8 08:56:53 2024
InstallationDate: Installed on 2023-11-02 (127 days ago)
InstallationMedia: Ubuntu 24.04 "Noble Numbat" - Daily amd64 (20231101)
PackageArchitecture: all
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: software-properties
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[corrado venturini (corradoventu)]

I don't know how to add proposed in my ubuntu sources, please help:

 ## See the sources.list(5) manual page for further settings.
Types: deb
URIs: http://archive.ubuntu.com/ubuntu/
Suites: noble noble-updates noble-backports
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

## Ubuntu security updates. Aside from URIs and Suites,
## this should mirror your choices in the previous section.
Types: deb
URIs: http://security.ubuntu.com/ubuntu/
Suites: noble-security
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 2053228, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.