Can't run System Monitor in Ubuntu Unity 21.04

[Wiktor Nizio]

I can't run System Monitor in Ubuntu Unity 21.04. I reported a bug on Ubuntu Unity's tracker, but I've been told to report it here.

https://gitlab.com/ubuntu-unity/ubuntu-unity-issues/-/issues/82#note_539356065

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: gnome-system-monitor 40.0-1
ProcVersionSignature: Ubuntu 5.11.0-11.12-generic 5.11.0
Uname: Linux 5.11.0-11-generic x86_64
ApportVersion: 2.20.11-0ubuntu61
Architecture: amd64
CurrentDesktop: Unity:Unity7:ubuntu
Date: Sat Mar 27 15:32:16 2021
InstallationDate: Installed on 2021-03-27 (0 days ago)
InstallationMedia: Ubuntu Unity 21.04
SourcePackage: gnome-system-monitor
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Maik (maik-adamietz)]

So far it only affects Ubuntu Unity 21.04. Main Ubuntu 21.04 doesn't seem to have this issue and System monitor opens without any problem.

[Maik (maik-adamietz)]

This is the error i get when trying to run the system monitor from a terminal:

ubuntu@ubuntu:~$ gnome-system-monitor

(gnome-system-monitor:5412): Gtk-WARNING **: 17:49:22.082: Theme parsing error: gtk.css:6083:16: Junk at end of value for color

(gnome-system-monitor:5412): Gtk-CRITICAL **: 17:49:22.765: gtk_box_pack: assertion '_gtk_widget_get_parent (child) == NULL' failed

(gnome-system-monitor:5412): Handy-ERROR **: 17:49:22.941: gtk_window_set_titlebar() is not supported for HdyWindow
Trace/breakpoint trap (core dumped)

[Sebastien Bacher (seb128)]

Thank you for your bug report. The issue seems to be a theme one though, which one do you use? Is it provided in Ubuntu, in which case it should be reassigned to that component

[Wiktor Nizio (skrzypce)]

It doesn't say "Theme parsing error" when the theme is Adwaita or Ambiance. But still, it does not run.

[Sebastien Bacher (seb128)]

Could you try to obtain a backtrace following the instructions at http://wiki.ubuntu.com/DebuggingProgramCrash and upload the backtrace (as an attachment) to the bug report. This will greatly help us in tracking down your problem.

[Robert Roth (evfool)]

@seb128, the crash in my opinion is not related to the theme, but rather the same as reported upstream https://gitlab.gnome.org/GNOME/gnome-system-monitor/-/issues/182, coming from the migration to LibHandy, on non-GNOME environments. The issue was fixed upstream with commit https://gitlab.gnome.org/GNOME/gnome-system-monitor/-/commit/69224a7b27a85e7485fb47f9e9f14ce674798c28 on master and with commit https://gitlab.gnome.org/GNOME/gnome-system-monitor/-/commit/ba93af5b3e429db5a9c4dd7e2d06b800735a9071 on the gnome-40 stable branch, and will be available with the next stable release.

[Wiktor Nizio (skrzypce)]

Sorry, I do not understand how do follow these instructions. I don't know how to obtain a backtrace.

[Khurshid Alam (khurshid-alam)]

This is gtk-nocsd bug. Gtk-nocsd is not compatible with new HdyWindow. The debian version is unmaintained as of now.

The new code is https://github.com/ZaWertun/gtk3-nocsd.

Perhaps one can try with that library.

Note: If you install gnome-session you will need this patch from https://bugs.launchpad.net/ubuntu/+source/gtk3-nocsd/+bug/1745206

[Khurshid Alam (khurshid-alam)]

Edit: It seems the issue is fixed with https://gitlab.gnome.org/GNOME/gnome-system-monitor/-/commit/ba93af5b3e429db5a9c4dd7e2d06b800735a9071

[Wiktor Nizio (skrzypce)]

Still present in Ubuntu Unity 21.04 Beta.

[Maik (maik-adamietz)]

Confirming that the issue is still present in Ubuntu Unity 21.04 Beta.

[Launchpad Janitor (janitor)]

This bug was fixed in the package gnome-system-monitor - 40.0-2

---------------
gnome-system-monitor (40.0-2) experimental; urgency=medium

  * debian/patches/git_nongnome_segfault.patch:
    - Dropped non-gnome workaround causing crash (lp: #1921583)

 -- Sebastien Bacher <email address hidden> Tue, 30 Mar 2021 11:10:35 +0200

[Wiktor Nizio (skrzypce)]

Verified in Ubuntu Unity 21.04 Beta.

To access the fix, please select "Pre-released" in Software & Updates -> Developer Options.

[Maik (maik-adamietz)]

A new iso of Ubuntu Unity 21.04 has been released today. After testing it i can confirm that System Monitor starts up fine. The issue is solved.