gnome-shell crashes when locking screen while dock widget is in focus

[Sander Bollen]

gnome-shell crashes with signal 11 (segmentation fault) when I try to lock the screen while a widget in the dock is in focus. The end result is that the screen either does not lock, and gnome-shell reloads, or it hangs (can move mouse, but mouse clicks or keyboard presses don't seem to have any effect). Either way no screen lock occurs.

This is on a dual-screen setup, where I have the dock visible on both screens.

Steps to reproduce:

1) Open a terminal (or any app, terminal is just an example)
2) Open a new terminal with cntrl+N
3) Click on the terminal icon on the dock, so it shows both instances of the terminal app
4) Try to lock the screen with super+L
5) Observe crash

Attached is the output of syslog at the exact moment the crash occurs.

Output of lsb_release -rd:
Description: Ubuntu 18.04.1 LTS
Release: 18.04

Output of apt-cache policy gnome-shell:
gnome-shell:
  Installed: 3.28.3-0ubuntu0.18.04.2
  Candidate: 3.28.3-0ubuntu0.18.04.2
  Version table:
 *** 3.28.3-0ubuntu0.18.04.2 500
        500 http://nl.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.28.1-0ubuntu2 500
        500 http://nl.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It sounds like some part of the system has crashed. To help us find the cause of the crash please follow these steps:

1. Look in /var/crash for crash files and if found run:
    ubuntu-bug YOURFILE.crash
Then tell us the ID of the newly-created bug.

2. If step 1 failed then look at https://errors.ubuntu.com/user/ID where ID is the content of file /var/lib/whoopsie/whoopsie-id on the machine. Do you find any links to recent problems on that page? If so then please send the links to us.

3. If step 2 also failed then apply the workaround from bug 994921, reboot, reproduce the crash, and retry step 1.

Please take care to avoid attaching .crash files to bugs as we are unable to process them as file attachments. It would also be a security risk for yourself.

[Kilian Pfeiffer (k1l1)]

I have a similar problem, the gnome shell crashes, part of the UI gets unresponsive, especially the dock is not disappearing, and overlaps over the applications. When I lock the session, the dock is still visible and programs can be started in locked state!

[Daniel van Vugt (vanvugt)]

Kilian, please log your own bug, firstly by finding a crash file in /var/crash and then running 'ubuntu-bug THEFILE.crash'.

[Kilian Pfeiffer (k1l1)]

Hi Daniel,
thanks for the response!
It seems like gnome shell does not completely crash (at least there is no crash file in /var/crash). Is there any other useful method to monitor this behavior?

[Daniel van Vugt (vanvugt)]

Kilian, yes, see step 2 in comment #2.

[Kilian Pfeiffer (k1l1)]

done -> https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1800587

[Sander Bollen (sander.h.bollen)]

Hello Daniel,

My apologies for the late reply.

This is the link I get from errors.ubuntu.com for this issue: https://errors.ubuntu.com/oops/a46fb0ae-d608-11e8-9484-fa163ee63de6

[Daniel van Vugt (vanvugt)]

Thanks. That is bug 1725312, which was fixed in 18.04 updates a month ago.

If you have any further issues then please open a new bug.