Lubuntu rejects password when resuming from automatic suspend

Question

History

I have Ubuntu. Because of its extraordinarily slow speed (especially after upgrading to 16.04 from 14.04, almost as slow as Windows), I installed lubuntu-desktop and now use Lubuntu. The change has greatly speeded my computer.
I am able to choose whether to boot into Ubuntu or Lubuntu each time I log in.
After this change, in Lubuntu, the automatic suspend would not work because it asked for the password. I fixed this using the solution to Authentication required before suspend.

Problem

When I resume from automatic suspend, I am greeted with an unusual login screen, which has only three elements:

The day and time
The title "Light Display Manager"
A prompt to enter a password without a user being displayed

When I enter my password, the prompt responds with, "Incorrect password". I have, of course, tried multiple times and typed my password carefully.

I cannot proceed from that screen, and even Ctrl+Alt+Delete doesn't work. I have to use REISUB. EDIT: I can also sign into a console (Ctrl+Alt+F1) and sudo reboot.

Extra notes

If I suspend manually, or if I use Ubuntu, the computer resumes properly with the correct login screen, accepting my password and allowing me to continue. Only the automatic suspend from Lubuntu gives this problem.

Question

How do I get the computer to resume correctly from automatic suspend when using Lubuntu?

The `lubuntu-desktop` metapackage installs the `xfce4-power-manager` so maybe the problem is that both `xfce4-power-manager` and `gnome-power-manager` are active. Try to disable suspend from the `gnome-power-manager` and enable it at xfce4-power-manager. — Thanos Apostolou, Aug 27 '16 at 14:44
@ThanosApostolou : Thanks, but unfortunately it doesn't help. — Paddy Landau, Aug 28 '16 at 12:36
@DKBose : Sorry, I'm not going to reformat my drive and do a full installation. I don't have that sort of time! — Paddy Landau, Aug 28 '16 at 12:37
Hmmm `light-locker` is also installed with `lubuntu-desktop`, so maybe try to disable it or remove it by `sudo apt purge light-locker`. — Thanos Apostolou, Aug 28 '16 at 13:39
@ThanosApostolou Thanks for your time. Unfortunately, neither disabling nor uninstalling light-locker helped. That's not really surprising, as Light Locker already knows that Xfce Power Manager is managing the power. I wonder if it would work to disable both Light Locker and Xfce Power Manager, and instead use whatever Ubuntu uses; but I don't know how to go about doing that. — Paddy Landau, Aug 28 '16 at 19:18
@PaddyLandau I would completely remove them by `sudo apt purge xfce4-power-manager xfce4-power-manager-plugins light-locker light-locker-settings` (I think the only reason that lubuntu uses the xfce4-power-manager instead of gnome's one is because it has a compatible indicator for lxde panel but you shouldnt care if the machine isn't a laptop ). Also check if the gnome-screensaver has a lock screen option and disable it to see if that's the problem. I can't think of anything else. — Thanos Apostolou, Aug 28 '16 at 19:36
@ThanosApostolou — I purged as you suggested (which also removes `lubuntu-desktop`), after which I had no way to suspend. So, I reinstalled the four packages plus `lubuntu-desktop`. After rebooting, it worked! Thank you. Please enter your suggestion as an answer, so that I can mark it as a solution. — Paddy Landau, Aug 29 '16 at 10:54
Seems to be a duplicate of https://askubuntu.com/questions/650954/unknown-xubuntu-screen-locker-password, which has an answer (remove `gnome-screensaver`). — Roger Lipscombe, Jun 29 '17 at 09:42

score 1 · Answer 1 · answered May 27 '20 at 14:54

Had similar problem. After a reboot, the screensaver password screen keeps asking for my password. Entering my password just keeps me going back to the same screensame password screen. Went to TTY and by sheer luck, i saw the out of space notice when I tried to uninstall light-locker. Turns out I had no more free space on my hdd.

Norbert Madarász · Answer 2 · 2019-02-16T11:28:00.510

0

For a quick temporary fix:

Login to a terminal, use CTRL+ALT+F1 or ...+F2 etc.
Kill light-locker as admin: sudo pkill light-locker

edited Feb 16 '19 at 11:28

answered Apr 06 '18 at 01:58

Norbert Madarász

109
1

this only solves the problem temporarily – João Pimentel Ferreira Jan 15 '19 at 20:40
It helped me when I needed to be quick. Too bad I pressed switch user which somehow killed my old session. – Sextus Empiricus Jan 25 '19 at 16:25

score 0 · Answer 3 · answered Jan 15 '19 at 20:38

0

This solved my problem

sudo apt remove gnome-screensaver

There is a conflict between screensavers as LightDM starts up gnome-screensaver when the device goes into suspend at the lock/login screen.

answered Jan 15 '19 at 20:38

João Pimentel Ferreira

988
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14
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score -1 · Answer 4 · edited May 10 '18 at 18:32

-1

Edit /etc/lightdm/users.conf as administrator. In the [UserList] section, make sure you have

hidden-users=nobody nobody4 noaccess lightdm

(user lightdm is often missing)

edited May 10 '18 at 18:32

Zanna

69,223
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answered Jul 25 '17 at 14:51

ced

1

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Thank you for the reply, @ced. I had other issues that forced me to reinstall Lubuntu from scratch. So, I can't check if your solution would have worked :( Incidentally, you used Windows backslash instead of the normal forward slash for the path :D – Paddy Landau Jul 25 '17 at 14:57
Oops. I typed the path manually. Old habits are difficult to quit. Ashamed. – ced Jul 25 '17 at 16:34
tried and doesn't work! – João Pimentel Ferreira Jan 15 '19 at 20:28

Lubuntu rejects password when resuming from automatic suspend

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4 Answers4