update-manager crashed with TypeError in _look_busy(): constructor returned NULL

Thanks for taking the time to report this bug and helping to make Ubuntu better. We appreciate the difficulties you are facing, but this appears to be a "regular" (non-security) bug. I have unmarked it as a security issue since this bug does not show evidence of allowing attackers to cross privilege boundaries nor directly cause loss of data/privacy. Please feel free to report any other bugs you may find.

I can't reproduce this exact error, but I do get an error if the Gdk imported is version 4:

>>> from gi.repository import Gdk
<stdin>:1: PyGIWarning: Gdk was imported without specifying a version first. Use gi.require_version('Gdk', '4.0') before import to ensure that the right version gets loaded.
>>> Gdk.Cursor.new(Gdk.CursorType.WATCH)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: type object 'Cursor' has no attribute 'new'. Did you mean: 'newv'?

After all the new constructor only exists in Gdk 3.

I see two possible solutions:

1. Do as suggested and require the specific Gdk version with
   gi.require_version('Gdk', '3.0')

2. Use a constructor that exists in both Gdk versions:
   Gdk.Cursor.new_from_name("wait", None)

1. Testing that the other way around (3->4), I get

--->
% ./update-manager --data-dir=$PWD/data
Traceback (most recent call last):
  File "/home/nteodosio/canonical/ubuntu-pro/update-manager/./update-manager", line 38, in <module>
    from UpdateManager.UpdateManager import UpdateManager
  File "/home/nteodosio/canonical/ubuntu-pro/update-manager/UpdateManager/UpdateManager.py", line 24, in <module>
    gi.require_version('Gdk', '4.0')
  File "/usr/lib/python3/dist-packages/gi/__init__.py", line 113, in require_version
    raise ValueError('Namespace %s is already loaded with version %s' %
ValueError: Namespace Gdk is already loaded with version 3.0
<---

So I think this would just introduce such error in the other direction (4->3).

2. Actually the new_from_name constructor has different signatures in Gdk 3 and 4.

I also couldn't reproduce the issue in an unaltered Noble beta ISO.

As such, I suggest to let this sit unattended until confirmed.

> So I think this would just introduce such error in the other direction (4->3).

That was a short-sighted conclusion, adding the require_version to the entry point script will do.

This bug was fixed in the package update-manager - 1:24.04.5

---------------
update-manager (1:24.04.5) noble; urgency=medium

  * Require Gdk3, as at least one function is used that is not in Gdk4
    (LP: #2054197).
  * Run linting tests during build time as well.

  [ Calvin Mwadime ]
  * d/control: Depend on ubuntu-pro-client instead of ubuntu-advantage-tools.
    (LP: #2057559)

 -- Sebastien Bacher <email address hidden> Tue, 16 Apr 2024 11:38:56 +0200