Plasma Login Manager doesn't start

Support KDE Plasma
1

I’ve tried to switch from SDDM to Plasma Login Manager:

sudo pacman -S plasma-login-manager
sudo systemd-sysusers
sudo systemctl disable sddm
sudo systemctl enable plasmalogin

But it doesn’t work, here’s what it says:

plasmalogin-helper[1443]: [PAM] Starting..
plasmalogin-helper[1443]: [PAM] Authenticating…
plasmalogin-helper[1443]: pam_warn(plasmalogin-greeter:auth): function=[pam_sm_authenticate] flags=0 service=[plasmalogin-greeter] terminal=[] user=[plasmalogin] ruser=[] rhost=[]
plasmalogin-helper[1443]: [PAM] authenticate: Authentication failure
plasmalogin-helper[1443]: [PAM] returning.
plasmalogin[1431]: Error from greeter session: “Authentication failure”
plasmalogin-helper[1443]: [PAM] Asked to close the session but it wasn’t previously open
plasmalogin-helper[1443]: [PAM] Ended.
plasmalogin[1431]: Auth: plasmalogin-helper exited with 1
plasmalogin[1431]: Greeter stopped. PLASMALOGIN::Auth::HELPER_AUTH_ERROR

Did anyone try it successfully?

2

:bangbang: Tip :bangbang:

When posting terminal output, copy the output and paste it here, wrapped in three (3) backticks, before AND after the pasted text. Like this:

```
pasted text
```

Or three (3) tilde signs, like this:

~~~
pasted text
~~~

This will just cause it to be rendered like this:

Sed
sollicitudin dolor
eget nisl elit id
condimentum
arcu erat varius
cursus sem quis eros.

Instead of like this:

Sed sollicitudin dolor eget nisl elit id condimentum arcu erat varius cursus sem quis eros.

Alternatively, paste the text you wish to format as terminal output, select all pasted text, and click the </> button on the taskbar. This will indent the whole pasted section with one TAB, causing it to render the same way as described above.

Thereby increasing legibility thus making it easier for those trying to provide assistance.

For more information, please see:

As I’m a moderator on the forum, I have taken the liberty of doing this for you, this time.

:bangbang::bangbang: Additionally

If your language isn’t English, please prepend any and all terminal commands with LC_ALL=C. For example:

LC_ALL=C bluetoothctl

This will just cause the terminal output to be in English, making it easier to understand and debug.

Note that the above text is partially pre-prepared as a general introduction for new forum Users. Please take the time to to understand how it is done and encourage quality responses.

3

There is a warning on the Plasma Login Manager GitLab page:

Caution

It is not recommended to install this on your system — you should use a virtual machine instead. Installing this on real hardware will leave behind files not trivially uninstallable and could leave your system in a non-functional state.

Also, did you actually look at the output when you installed it? You don’t need to create the systemd user, as it is done automatically when the repo package is installed, as can be seen in my paclog output after installing it:

[2026-01-10T08:49:49+1100] [ALPM] transaction started
[2026-01-10T08:49:49+1100] [ALPM] installed plasma-login-manager (6.4.git20250712-1.1)
[2026-01-10T08:49:49+1100] [ALPM] transaction completed
[2026-01-10T08:49:49+1100] [ALPM] running '20-systemd-sysusers.hook'...
[2026-01-10T08:49:49+1100] [ALPM-SCRIPTLET] Creating group 'plasmalogin' with GID 946.
[2026-01-10T08:49:49+1100] [ALPM-SCRIPTLET] Creating user 'plasmalogin' (PLASMALOGIN Greeter Account) with UID 946 and GID 946.
[2026-01-10T08:49:49+1100] [ALPM] running '30-systemd-daemon-reload-system.hook'...
[2026-01-10T08:49:49+1100] [ALPM] running '30-systemd-daemon-reload-user.hook'...
[2026-01-10T08:49:49+1100] [ALPM] running '30-systemd-tmpfiles.hook'...
[2026-01-10T08:49:50+1100] [ALPM] running '30-systemd-update.hook'...
[2026-01-10T08:49:50+1100] [ALPM] running 'dbus-reload.hook'...
[2026-01-10T08:49:50+1100] [ALPM] running 'update-desktop-database.hook'...

Although you do still need to enable/disable the relevant systemd services (by the way, you don’t need to use sudo for that - systemd will prompt you for a password when required)

I couldn’t get it to run either after running systemctl disable sddm & systemctl enable plasmalogin & then rebooting. This is the journal output:

journalctl -b -1 | grep -E plasmalogin\|sddm
Jan 10 08:57:28 scott-ser plasmalogin[727]: Initializing...
Jan 10 08:57:28 scott-ser plasmalogin[727]: Starting...
Jan 10 08:57:28 scott-ser plasmalogin[727]: Logind interface found
Jan 10 08:57:28 scott-ser plasmalogin[727]: Adding new display...
Jan 10 08:57:28 scott-ser plasmalogin[727]: Using VT 1
Jan 10 08:57:28 scott-ser plasmalogin[727]: Display server started.
Jan 10 08:57:28 scott-ser plasmalogin[727]: Socket server starting...
Jan 10 08:57:28 scott-ser plasmalogin[727]: Socket server started.
Jan 10 08:57:28 scott-ser plasmalogin[727]: Greeter starting...
Jan 10 08:57:28 scott-ser plasmalogin-helper[731]: [PAM] Starting...
Jan 10 08:57:28 scott-ser plasmalogin-helper[731]: [PAM] Authenticating...
Jan 10 08:57:28 scott-ser plasmalogin-helper[731]: pam_warn(plasmalogin-greeter:auth): function=[pam_sm_authenticate] flags=0 service=[plasmalogin-greeter] terminal=[<unknown>] user=[plasmalogin] ruser=[<unknown>] rhost=[<unknown>]
Jan 10 08:57:28 scott-ser plasmalogin-helper[731]: [PAM] authenticate: Authentication failure
Jan 10 08:57:28 scott-ser plasmalogin-helper[731]: [PAM] returning.
Jan 10 08:57:28 scott-ser plasmalogin[727]: Error from greeter session: "Authentication failure"
Jan 10 08:57:28 scott-ser plasmalogin-helper[731]: [PAM] Asked to close the session but it wasn't previously open
Jan 10 08:57:28 scott-ser plasmalogin-helper[731]: [PAM] Ended.
Jan 10 08:57:28 scott-ser plasmalogin[727]: Auth: plasmalogin-helper exited with 1
Jan 10 08:57:28 scott-ser plasmalogin[727]: Greeter stopped. PLASMALOGIN::Auth::HELPER_AUTH_ERROR
Jan 10 08:59:39 scott-ser polkitd[653]: Operator of unix-process:1063:13007 FAILED to authenticate to gain authorization for action org.freedesktop.systemd1.manage-unit-files for system-bus-name::1.30 [systemctl enable sddm] (owned by unix-user:scotty)
Jan 10 08:59:57 scott-ser plasmalogin[727]: Signal received: SIGTERM
Jan 10 08:59:57 scott-ser plasmalogin[727]: Socket server stopping...
Jan 10 08:59:57 scott-ser plasmalogin[727]: Socket server stopped.
Jan 10 08:59:57 scott-ser systemd[1]: plasmalogin.service: Deactivated successfully.

I’m not going to investigate any further, as I’m happy at the moment with SDDM, and I use autologin anyway.

But it might be worth waiting until all the bugs are ironed out, and for Manjaro’s maintainers to make any distro-specific modifications to the configuration, before using plasma-login-manager on a non-virtual machine installation.

Also, even though I wasn’t able to boot to a desktop after enabling plasma-login-manager, I was able to switch to a TTY session and ran the following commands which got me back to my desktop:

systemctl enable sddm

systemctl disable plasmalogin

systemctl reboot
4

I had no problem reverting back to sddm. The question was only if someone could run it successfully and if so help me out with this one. But since you confirmed you can’t either maybe it is untested by Manjaro devs themselves.

I was curious since Fedora is going to run it by default and some Arch users are testing it right now.

1 Like
5

Same here

Jan 17 03:31:26 plasmalogin-helper[937]: [PAM] authenticate: Fehler bei Authentifizierung
Jan 17 03:31:26 plasmalogin[931]: Error from greeter session: "Fehler bei Authentifizierung"
Jan 17 03:31:26 plasmalogin-helper[937]: [PAM] Asked to close the session but it wasn't previously open
Jan 17 03:31:26 plasmalogin[931]: Auth: plasmalogin-helper exited with 1
Jan 17 03:33:44 plasmalogin[931]: Signal received: SIGTERM
6

Fedora expect to have it production ready by April 2027, so, it’s still early days; the best recommendation is don’t.

Wait for it to actually be ready for mainstream use.

Until that time, there will be generally no Support offered via the Manjaro forum, being that KDE Login Manager is currently experimental software.

1 Like