Gnome-shell won't lock screen anymore

[Nicolas Chambrier]

When I press the lock shortcut Gnome Shell won't lock screen: instead it "blinks" (top bar disappears for a moment) and comes back, no lock screen or password asked. Closing screen (laptop) does the same but I still get low consumption, so hibernation seems to be working, but there is no password asked after opening.

I get this error in dmesg:

```
[10413.140792] gnome-shell[28745]: segfault at fffffffffffffbc8 ip 00007f37ab2c6ec8 sp 00007ffdc4a371d0 error 5 in libst-1.0.so[7f37ab2a0000+2b000]
[10413.140798] Code: 00 00 48 8d 3d 57 78 00 00 e9 34 9c fd ff 0f 1f 40 00 41 57 41 56 41 55 41 54 55 53 48 83 ec 28 48 63 1d db 74 01 00 48 01 fb <48> 8b 6b 08 48 85 ed 74 17 48 83 c4 28 48 89 e8 5b 5d 41 5c 41 5d
```

I tried to "apt-get install --reinstall gnome-shell", or "uninstall --purge" it and install back, but nothing works. It has started right after an update 2 or 3 days ago, supposedly related to 19.04?

I obviously never disabled the password on lock screen :) by the way it's working perfectly if I chose standard GNOME desktop on login.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: gnome-shell 3.30.2-0ubuntu1.18.10.1
ProcVersionSignature: Ubuntu 4.18.0-18.19-generic 4.18.20
Uname: Linux 4.18.0-18-generic x86_64
ApportVersion: 2.20.10-0ubuntu13.3
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Apr 30 14:33:31 2019
DisplayManager: gdm3
ExecutablePath: /usr/bin/gnome-shell
InstallationDate: Installed on 2018-04-13 (381 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Beta amd64 (20180404)
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fr_FR.UTF-8
 SHELL=/bin/zsh
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to cosmic on 2018-10-24 (188 days ago)

[Sebastien Bacher (seb128)]

Thank you for your bug report. Do you get a report collected in /var/crash?
It would be useful to install the debug packages (https://wiki.ubuntu.com/Debug%20Symbol%20Packages) and get a backtrace (https://wiki.ubuntu.com/Backtrace)

[Sebastien Bacher (seb128)]

Do you use extensions? Could you maybe try with a new user account to see if it has the same issue?

[Nicolas Chambrier (naholyr-gmail)]

1. I cleared /var/crash and then reproduced the bug: nothing was created. Should I do something more?

2. I installed the "gnome-shell-dbgsym" package, the procedure to generate a backtrace may take me some time so I'll do it later I'll add it here ASAP

3. I use extensions, I try right now with another user (as it will close the browser ;)) I let you know in a few minutes.

[Nicolas Chambrier (naholyr-gmail)]

3 (bis). I tried with a fresh new user, it worked as intended. I'll try to disable all extensions to check if it's related to this, or another configuration. Could the segfault come from something like this?

[Nicolas Chambrier (naholyr-gmail)]

3 (ter). I disabled all extensions, then restarted gnome-shell, and now it works well ;) nicely spotted, I feel ashamed I didn't think about this first… Now I'll re-enabled them one by one, and give a report to the faulty one's author. All good here I guess!

[Nicolas Chambrier (naholyr-gmail)]

For the record, it's "Draw on Your Screen" https://extensions.gnome.org/extension/1683/draw-on-you-screen/ (sadly, it was cool for my trainings)