attempting to use idle brightness in lxqt-powermanagement leads to crash on 22.04.4 LTS

[Rick Sayre]

I have exactly the same problem as OP here (and the others who chime in):
https://askubuntu.com/questions/1422776/energy-manager-error-when-reducing-screen-brightness-during-inactivity

Reported 1 year 8 months ago, still seems broken

LxQT Power Manager:
In the settings section for "inactivity", I check the option "enable backlight change", in order to reduce the screen brightness after 1 minute of inactivity.

If I press the "Check Backlight" button, nothing happens.

Upon completion of 1 minute of inactivity, instead of the screen brightness being reduced, I see the power/battery icon disappear, then reappear a few times, then the system displays an alert of multiple manager crash errors, resulting in its autorun being disabled.

Adjusting screen brightness via "lxqt-config-brightness" from "lxqt-config" works fine

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: lxqt-powermanagement 0.17.1-0ubuntu1
ProcVersionSignature: Ubuntu 6.5.0-28.29~22.04.1-generic 6.5.13
Uname: Linux 6.5.0-28-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: LXQt
Date: Wed Apr 24 10:03:12 2024
InstallationDate: Installed on 2023-10-31 (175 days ago)
InstallationMedia: Lubuntu 22.04.1 LTS "Jammy Jellyfish" - Release amd64 (20220809)
SourcePackage: lxqt-powermanagement
UpgradeStatus: No upgrade log present (probably fresh install)

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

You mention it was "Reported 1 year 8 months ago" if so please provide the bug report link, as you only provided reference to a support site (which isn't a bug report). FYI: I'd have appreciated a picture of the image in english; the picture provided via link to askubuntu alas wasn't in english.

If you update your LXQt using Lubuntu backports, does the issue still occur ??

ie. your report here mentions using

lxqt-powermanagement 0.17.1-0ubuntu1

where the version in Lubuntu backports (for 22.04/jammy) is

1.4.0-0ubuntu2~ppa1

[Rick Sayre (whorfin)]

Thank you for the timely reply.

I assumed the support site was a report, my apologies, as I assumed it was monitored.
I found a very similar report, which I presume is "proper", here:
https://bugs.launchpad.net/ubuntu/+source/lxqt-powermanagement/+bug/1987036
and indeed this is a few days older than the support site reference.

I figured the description was sufficient, but will attach a brand-new screenshot. In English as requested.

I installed backports and observed exactly the same behavior.
Logs showed repeats of the crash until the rate-limiting shutdown of restarts for lxqt-powermanager:
Apr 24 17:48:54 Konnekt kernel: lxqt-powermanag[20433]: segfault at e8e ip 00007e8466908059 sp 00007ffeed791208 error 4 in libQt5Core.so.5.15.3[7e846688e000+30f000] likely on CPU 0 (core 0, socket 0)
Apr 24 17:48:54 Konnekt kernel: Code: 31 d2 f7 f1 49 8b 40 08 83 c2 01 48 63 f2 48 8d 04 f0 29 d1 74 d8 89 c9 48 8d 0c c8 eb 0c 0f 1f 00 48 83 c0 08 48 39 c8 74 c4 <48> 8b 10 49 39 d0 74 ef 49 89 d0 4c 89 c0 c3 0f 1f 84 00 00 00 00

This was with the backports version:
$ lxqt-powermanagement -v
lxqt-powermanagement 1.4.0
liblxqt 1.4.0
Qt 5.15.3