Desktop freezes (no keyboard input, mouse still works but can't click on anything)

[The Pthyister]

As in the summary ;

Desktop freezes (no keyboard input, mouse still works but can't click on anything). Workaround has been to ctrl-alt-f2 => login => kill the xfce4-screensaver process manually using htop (F3 for search, type in the search field: 'xfce4-screensaver' => F9 => SIGTERM).

Judging from the amount of forum posts, this has apparently been a problem for years. Any chances on being able to disable the xfce4-screensaver process altogether? I frankly don't need it. All power saving options are disabled (as they are supposed to be when running on an RPi).

Would seem to me that Xfce is trying to switch to the login screen for safety reasons, but is unable to do so, hence resulting not only the desktop being completely visible (that's why I marked this as a security vulnerability) but also making it hard or in some instances impossible for an inexperienced user to do anything about it.

I did not experience this issue with Ubuntu Server 64-bit 18.04.4LTS+xubuntu desktop running on the same RPi4B - iẗ́s a newcomer that's surfaced with the 20.04 LTS. The Pi4B has the latest publicly available firmware and kernel revision.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xfce4-screensaver 0.1.10-0ubuntu1
ProcVersionSignature: User Name 5.4.0-1011.11-raspi 5.4.34
Uname: Linux 5.4.0-1011-raspi aarch64
ApportVersion: 2.20.11-0ubuntu27
Architecture: arm64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Thu May 14 12:54:54 2020
SourcePackage: xfce4-screensaver
UpgradeStatus: No upgrade log present (probably fresh install)

[The Pthyister (pthyister)]

I tried some of the troubleshooting tips and workaround suggestions from:

https://wiki.ubuntu.com/X/Troubleshooting/Freeze

I can replicate the freezing problem by typing into a desktop terminal window:

sleep 1; xset s activate

That causes the UI to freeze the usual way, as described in the initial bugreport.

[The Pthyister (pthyister)]

I'm trying the advice given on the Ubuntu wiki;

 sleep 1; xset dpms force off

And see where that leads.

[Bernie Hoeneisen (bhoeneis)]

As a work-around I installed xscreensaver and removed xfce4-screensaver

$ sudo apt-get install xscreensaver
$ sudo apt-get remove xfce4-screensaver

After logout and login, I have not experienced these issues anymore.

[Himura (glagol)]

Are you running xubuntu on bare metal or VM? We have this bug for VM https://bugs.launchpad.net/ubuntu/+source/xfce4-screensaver/+bug/1871817

[The Pthyister (pthyister)]

> Himura (glagol) wrote on 2020-09-08:
> Are you running xubuntu on bare metal or VM? We have this bug for VM https://bugs.launchpad.net/ubuntu/+source/xfce4-screensaver/+bug/1871817

Bare metal (Raspberry Pi4B, 4GB), but this has long since been solved since I've moved on to a newer distro version (20.10 groovy) -- thanks!

[Launchpad Janitor (janitor)]

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