A circumstance in which 'Apply the Update' does nothing

[LinuxOnTheDesktop]

Describe the bug
Updating mintupdate (itself) on the command line, whilst mintupdate is running, led mintupdate to offer an 'Apply the update' button that did nothing. I pressed that button thrice; each time after some whirring I was back seeing the same thing. I presume that having done the following is (well, combined with mintupdate) the problem.

$ sudo apt upgrade
[. . .]
The following packages have been kept back:
  python3-update-manager transmission-common transmission-gtk
The following packages will be upgraded:
  dnsmasq-base firefox firefox-locale-en google-chrome-stable libc-bin libc-dev-bin libc-devtools libc6
  libc6:i386 libc6-dbg libc6-dev libc6-i386 libsqlite3-0:i386 libsqlite3-0 libsqlite3-dev linux-firmware
  linux-generic-hwe-22.04 linux-generic-hwe-22.04-edge linux-headers-generic-hwe-22.04
  linux-headers-generic-hwe-22.04-edge linux-image-generic-hwe-22.04 linux-image-generic-hwe-22.04-edge
  locales mint-mirrors mint-upgrade-info mintupdate openssh-client openssh-server openssh-sftp-server
  sqlite3 ssh ssh-askpass-gnome
32 to upgrade, 0 to newly install, 0 to remove and 3 not to upgrade.
24 standard LTS security updates
[. . .]
Do you want to continue? [Y/n] y
[. . .]

Screenshots

To Reproduce
Steps to reproduce the behavior:

1. Have mintupgrade running.
2. sudo apt upgrade and say y.
3. Click 'apply updates' within mintupgrade.

Expected behavior
mintupgrade should restart or prompt for a restart.

Distribution:

• [X ] Linux Mint
• LMDE
• Other (please specify)

Software version:
6.03

Logs:
01.11@08:59 ++ Launching Update Manager
01.11@08:59 ++ Changes to the package cache detected, triggering refresh
01.11@08:59 ++ Package cache location not found, disabling cache monitoring
01.11@08:59 ++ Initial refresh will happen in 0 day(s), 0 hour(s) and 10 minute(s)
01.11@08:59 ++ Inhibited power management
01.11@08:59 ++ Starting refresh (local only)
01.11@08:59 ++ Tracker: Mintupdate update button was pressed recently: 23 days ago
01.11@08:59 ++ Found 7 software updates
01.11@08:59 ++ Refresh finished
01.11@08:59 ++ Resumed power management
01.11@09:09 ++ Update Manager is in tray mode, performing initial refresh
01.11@09:09 ++ Inhibited power management
01.11@09:09 ++ Starting refresh (retrieving lists of updates from remote servers)
01.11@09:09 ++ Refreshing available Cinnamon updates from the server
01.11@09:09 ++ Refreshing available Flatpak updates
01.11@09:09 ++ Found 7 software updates
01.11@09:09 ++ Refresh finished
01.11@09:09 ++ Resumed power management
01.11@09:09 ++ Recurring refresh will happen in 0 day(s), 1 hour(s) and 59 minute(s)
01.11@17:37 ++ Update Manager is in tray mode, performing recurring refresh
01.11@17:37 ++ Inhibited power management
01.11@17:37 ++ Starting refresh (retrieving lists of updates from remote servers)
01.11@17:37 ++ Refreshing available Cinnamon updates from the server
01.11@17:37 ++ Refreshing available Flatpak updates
01.11@17:37 ++ Found 7 software updates
01.11@17:37 ++ Refresh finished
01.11@17:37 ++ Resumed power management
01.11@17:37 ++ Recurring refresh will happen in 0 day(s), 1 hour(s) and 59 minute(s)
01.11@19:37 ++ Update Manager is in tray mode, performing recurring refresh
01.11@19:37 ++ Inhibited power management
01.11@19:37 ++ Starting refresh (retrieving lists of updates from remote servers)
01.11@19:37 ++ Refreshing available Cinnamon updates from the server
01.11@19:37 ++ Refreshing available Flatpak updates
01.11@19:38 ++ Found 1 software updates
01.11@19:38 ++ Refresh finished
01.11@19:38 ++ Resumed power management
01.11@19:38 ++ Recurring refresh will happen in 0 day(s), 1 hour(s) and 59 minute(s)
01.12@18:53 ++ Inhibited power management
01.12@18:53 ++ Install requested by user
01.12@18:53 ++ Will install mintupdate
01.12@18:53 ++ Ready to launch synaptic

(synaptic:279667): Gtk-CRITICAL **: 18:53:07.706: gtk_widget_hide: assertion 'GTK_IS_WIDGET (widget)' failed
01.12@18:53 ++ Return code:0
01.12@18:53 ++ Install failed
01.12@18:53 ++ Resumed power management
01.12@18:53 ++ Inhibited power management
01.12@18:53 ++ Install requested by user
01.12@18:53 ++ Will install mintupdate
01.12@18:53 ++ Ready to launch synaptic

(synaptic:279898): Gtk-CRITICAL **: 18:53:21.485: gtk_widget_hide: assertion 'GTK_IS_WIDGET (widget)' failed
01.12@18:53 ++ Return code:0
01.12@18:53 ++ Install failed
01.12@18:53 ++ Resumed power management
01.12@18:56 ++ Inhibited power management
01.12@18:56 ++ Install requested by user
01.12@18:56 ++ Will install mintupdate
01.12@18:56 ++ Ready to launch synaptic

(synaptic:281887): Gtk-CRITICAL **: 18:56:22.941: gtk_widget_hide: assertion 'GTK_IS_WIDGET (widget)' failed
01.12@18:56 ++ Return code:0
01.12@18:56 ++ Install failed
01.12@18:56 ++ Resumed power management

Additional context
Manually closing and then re-running mintupdate produced a mintupdate that was unresponsive for a slightly throwingly long amount of time - some ten seconds (on a slow-ish computer), with no spinner showing - but then all was well, including a menu option offering the upgrade to Virginia.

[simounn]

I saw a different issue but with similar symptom. The GUI mintupdate offered to update itself from 6.0.8 to 6.0.9. Clicked "Apply the Update" and nothing seemed to happen. Quit the GUI updater, tried to run mintupdate command from terminal but it failed and output these messages:

After restart of OS running mintupdate from terminal would work and was the new version 6.0.9. I have a timeshift snapshots so can restore to before the update if this is helpful to diagnose the bug.