Error when attempting to save changes in Qubes Global Config

[kennethrrosen]

How to file a helpful issue

Qubes OS release

4.2.0-rc3

Brief summary

When attempting to apply or ok settings in QUbes OS Global config, changes are not saved for exceptions to updates checker and update proxy.

Steps to reproduce

Open Qubes OS Global Config.
Enable Checking for updates for all existing qubes
Check except the following qubes...
Select a qube and Apply
Or change update proxy from sys-net to whonix-16

Expected behavior

Changes are applied, dialogue exists.

Actual behavior

The following error occurs, and no changes are saved:

The following error occurred: Command '['/usr/lib/qubes/qubes-rpc-multiplexer','policy.Replace+50-config-updates','dom0']' returned non-zero exit status 1.

[UndeadDevel]

Could be related to #8753, though I am not seeing the mentioned error message and the change is actually applied "under the hood", just not reflected in the UI. I've updated that other issue to reflect the fact that it affects the update exceptions list as well.

Should this issue indeed be separate and be about the change not being effected at all (as opposed to merely the UI not reflecting it) then I can't reproduce this issue.

[alimirjamali]

Possibly related: #8014

[kennethrrosen]

And may soon be fixed with: #9062