Input devices stop working after logout or switch-user

[Ananth P]

laptop: HP G42
Ubuntu: 18.04 LTS

After clicking logout or switch user, once the system reaches the greeter/login screen, input devices -- keyboard, mouse, touchpad -- stop working, making it impossible to login back or shutdown.

Initially I thought the system is frozen, but log shows that it still responds to lid open/close, usb plug/unplug events, scheduled background tasks etc. Only the input devices, both onboard and external, are not usable. There's an external monitor attached to the laptop, and it shows the greeter and changes when lid is open or closed.

What works:

* logging in during fresh boot. Keyboard and mouse work at the greeter.
* suspend/resume, lock/unlock screen. I'm able to enter password and get back to my session.
* shutdown/restart while logged in.

What doesn't work:

* logout
* switch user

17.10 and other previous versions of ubuntu didn't have this issue on the same machine.

Workaround: restart gdm3 from a remote client.

[Daniel van Vugt (vanvugt)]

The problem you describe sounds like the secondary issue in bug 1766137 that was fixed only a few hours ago.

Please wait a few hours/days (for the update to propagate to everyone), update your system, and if the problem persists then please run:

   dpkg -l > dpkg.txt

and send us the resulting dpkg.txt

[Ananth P (ananthp)]

Problem persists even after updating gdm3 to 3.28.2-0ubuntu1.2 and restarting.

Attached `dpkg -l` output.

[Daniel van Vugt (vanvugt)]

Do you find any crash files in /var/crash/ ?

Also, what links do you find at https://errors.ubuntu.com/user/ID
(where ID is the contents of /var/lib/whoopsie/whoopsie-id on the machine) ?

[Ananth P (ananthp)]

My /var/crash has 3 crashes currently, none of them at the time of the problem:

* update manager
* puredata
* apport-gtk

errors.ubuntu.com has a longer list, includes nautilus, audacity, xwayland, gvfs-backends. (gdm3 is not in the list).

I brought the system to the same frozen state again (happens everytime I log out), logged in through ssh, didn't see any change in /var/crash. None shows up at journalctl either (attachment to original post). Could it be possible that it's not really a crash but some invalid state?

Let me know if I can get some additional log/info through ssh when the machine is in problem state.

[Launchpad Janitor (janitor)]

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

[Michal Pasniewski (michalp-y)]

In addition to the above symptoms, I had "black screen" after switching user but keyboard non-responsive.

I ssh'd from a different machine and could only find (in dmesg) "rfkill: input handler disabled".

Switching to lightdm via "sudo dpkg-reconfigure lightdm" got switching users to work.

[Daniel van Vugt (vanvugt)]

Michal, please open a separate bug of your own.

[[e-mail] (frankjstrike)]

For it works when I log out, but if I close the lid and open it up again, then I am unable to use the keyboard.