Arch Linux

I can confirm this bug, it still persists in systemd version 246.2.

I can confirm this bug, it still persists in systemd version 246.2-1

I would like to add information that there is missing "switch user" option not only in the lockscreen, but also in the "start menu".

It looks like in systemd 246 they deprecated the CanMultiSession property that SDDM probably depends on. https://github.com/systemd/systemd/commit/8f8cc84ba4612e74cd1e26898c6816e6e60fc4e9#diff-84655d62bac1ad22622cff8acddd395dR299

The property still exists and is set to "true" but because they added SD_BUS_VTABLE_HIDDEN hidden from introspection which I suspect that SDDM need for some reason (I'm just guessing on that, honestly). The CanMultiSession property is still there and you can confirm it returns "true" on 246 with the following command: `busctl get-property org.freedesktop.login1 /org/freedesktop/login1/seat/seat0 org.freedesktop.login1.Seat CanMultiSession`. You can also confirm it doesn't appear in introspection by withholding the CanMultiSession property name from the previous command and hitting the tab key which will introspect the interface and show you the available properties - CanMultiSession will be missing.

I don't use Plasma or SDDM and don't know much about but it does appear to depend on the CanMultiSession property https://github.com/sddm/sddm/blob/cf4c3caf058ea81d0e61c2087493623faac56a3f/data/interfaces/org.freedesktop.login1.Seat.xml#L11

Try opening a bug with upstream SDDM as well if one doesn't already exist.

I experience the same behaviour when logging in to Plasma via LightDM, so I think it doesn't depend on the greeter.

Has https://github.com/systemd/systemd/commit/8f8cc84ba4612e74cd1e26898c6816e6e60fc4e9 been confirmed as the cause by bisection or testing that commit and its parent?

I can confirm this bug, it still persists in systemd version 246.2-2, systemd-libs version 246.2-2 and systemd-sysvcompat version 246.2-2

As workaround, I downgraded to systemd version 245.7-1, systemd-libs version 245.7-1 and systemd-sysvcompat version 245.7-1 and the switch user option is back.

No bisection. I'm not running SDDM or Plasma. Just noticed the change in the systemd code and pointed it out as a possible issue.

Trying to build that commit or its parent, both fail due to missing https://github.com/systemd/systemd/commit/d17eabb1052e7c8c432331a7a782845e36164f01

Attached source bundle for the parent of 8f8cc84ba4612e74cd1e26898c6816e6e60fc4e9
If that works remove the ^ from commit=8f8cc84ba4612e74cd1e26898c6816e6e60fc4e9^ build again and see if it fails.

This bug still persists in systemd version 246.3-1, systemd-libs version 246.3-1 and systemd-sysvcompat version 246.3-1

As workaround, I downgraded to systemd version 245.7-1, systemd-libs version 245.7-1 and systemd-sysvcompat version 245.7-1 and the switch user option is back.

@Ravenman unfortunately there is nothing actionable in the bug report.
A fix needs to come from upstream. So a bug report needs to be opened with upstream, possibly both systemd and SDDM.
It would greatly speed up the process if the commit in systemd that introduced the change has been identified.
That is why I created the source bundle in [1] for affected users to test, see also [2].

[1] https://bugs.archlinux.org/task/67623#comment191966
[2] https://wiki.archlinux.org/index.php/Bisecting_bugs_with_Git

I'm not entirely sure that the login manager is at fault here. Definitely, systemd introduced the problem, but perhaps also kscreenlocker may need to adapt?
Or perhaps they rely on things that systemd/sddm are exporting.

The latest plasma 5.19.5 doesn't fix it. It's probably a bug of SDDM+systemd 246.

Do you not know how to build and install the systemd package in [1] or you are not willing to do so?

[1] https://bugs.archlinux.org/task/67623#comment191966

Both versions (with and without ^) build successfully, the first one does not have the bug while the second does.
I am guessing that GDM is not affected, only SDDM and possibly LightDM.

Thank you, so 8f8cc84ba4612e74cd1e26898c6816e6e60fc4e9 is confirmed as the systemd commit that introduced the issue causing change.

Can you please open upstream bug reports with SDDM [1] and systemd [2].

[1] https://github.com/sddm/sddm/issues
[2] https://github.com/systemd/systemd/issues

https://github.com/sddm/sddm/issues/1293
A different cause than suspected has been identified and there's a patch for it.

What patch?

Not sure why everyone's talking about sddm here... the KDE screen locker has nothing to do with sddm.

@arojas is the correct upstream bug tracker https://invent.kde.org/plasma/kscreenlocker/-/issues ?

No, KDE bug reports go to bugs.kde.org. In any case, KDE devs are aware of this and there is a fix in the works.

@dimosd I'm using GDM (gdm-3.36.3-6) and I'm affected too

You talk about this bug ?
https://bugs.kde.org/show_bug.cgi?id=423526

Still doesn't work for me

for me too

It is only partially fixed. It's okay in the application menu, but in the lock screen is a "switch user" possibility still missing.

That's odd. Both options were there after the first fix for me, but now I also don't have the lockscreen option, only the application menu one. What changed?

Please test 5.20

@arojas: It still doesn't work in a 5.20 version (application menu is okay, the lockscreen isn't)

Then please report upstream

Bug is still there for me - downgrading to systemd 245 brings back the user switch options but it is not possible to switch back to the 1st user from the lock screen without the 2nd user screen freezing.

Got it working by downgrading plasma-workspace and plasma-desktop as well (need both, cause of some kcm plugins that would otherwise be missing):

sudo pacman -U \
https://archive.org/download/archlinux_pkg_systemd/systemd-245.7-1-x86_64.pkg.tar.zst \
https://archive.org/download/archlinux_pkg_systemd-libs/systemd-libs-245.7-1-x86_64.pkg.tar.zst \
https://archive.org/download/archlinux_pkg_systemd-sysvcompat/systemd-sysvcompat-245.7-1-x86_64.pkg.tar.zst \
https://archive.org/download/archlinux_pkg_plasma-workspace/plasma-workspace-5.19.5-3-x86_64.pkg.tar.zst \
https://archive.org/download/archlinux_pkg_plasma-desktop/plasma-desktop-5.19.5-1-x86_64.pkg.tar.zst

/etc/pacman.conf:
IgnorePkg = systemd systemd-libs systemd-sysvcompat plasma-desktop plasma-workspace

Don't know if needed, but for better consistency I downgraded all of the plasma packages until this is fixed:

I can confirm that reverting 8f8cc84ba4612e74cd1e26898c6816e6e60fc4e9 in systemd-246 brings back user switching functionality.
Tested against KDE/SDDM and KDE/LightDM on Gentoo (sorry :).