gnome-shell 3.30.1-2ubuntu1.18.10.1 fails to start with JS ERROR: Error: No valid stylesheet found for 'Yaru/gnome-shell.css'

[Christian Sarrasin]

An upgrade to gnome-shell on 18.10 was recently released which made it impossible for me to log in to my DE. Upon typing my password, the gdm screen would disappear, only to re-appear a few seconds later. This was not a password typo as I didn't get the usual msg to that effect (I made at least 5 attempts, carefully typing my passwd).

I solved the issue by switching to a terminal screen (using CTRL+ALT+F6 I believe), logging in, analyzing recent changes through /var/log/apt/history.log. Beside the gnome-shell packages, a handful of Wayland packages were also upgraded as follows (I use X.org so left those alone):

Start-Date: 2018-12-19 09:13:20
Commandline: aptdaemon role='role-commit-packages' sender=':1.8821'
Upgrade: libwayland-egl1:amd64 (1.16.0-1ubuntu1, 1.16.0-1ubuntu1.1), keybase:amd64 (2.11.0-20181204152506.f11f4191e3, 2.13.0-20181218221625.d72e065cbe), gnome-tweak-tool:amd64 (3.30.1-1, 3.30.2-0ubuntu1), gnome-tweaks:amd64 (3.30.1-1, 3.30.2-0ubuntu1), libwayland-client0:amd64 (1.16.0-1ubuntu1, 1.16.0-1ubuntu1.1), gnome-shell-common:amd64 (3.30.1-2ubuntu1, 3.30.1-2ubuntu1.18.10.1), gnome-shell:amd64 (3.30.1-2ubuntu1, 3.30.1-2ubuntu1.18.10.1), libwayland-server0:amd64 (1.16.0-1ubuntu1, 1.16.0-1ubuntu1.1), libwayland-cursor0:amd64 (1.16.0-1ubuntu1, 1.16.0-1ubuntu1.1)
End-Date: 2018-12-19 09:13:31

I solved the issue by downgrading the just-updated gnome-shell packages as follows:

sudo apt install gnome-shell-common=3.30.1-2ubuntu1 gnome-shell=3.30.1-2ubuntu1

Having done this, I switched back to the GDM screen and managed to log in as normal. I couldn't find any smoking gun in system logs but please let me know if there's a way to collect any useful debug info.

One thing I'm using which differs from stock 18.10 is the System76 "Pop" theme (let me know if you need details). Presumably a theme cannot cause such issues and/or if the new version of gnome-shell is meant to be incompatible with themes other than Yaru, this should be clearly documented.

The problematic versions are the "Candidate" shown below:

gnome-shell:
  Installed: 3.30.1-2ubuntu1
  Candidate: 3.30.1-2ubuntu1.18.10.1
  Version table:
     3.30.1-2ubuntu1.18.10.1 500
        500 http://ch.archive.ubuntu.com/ubuntu cosmic-updates/main amd64 Packages
 *** 3.30.1-2ubuntu1 500
        500 http://ch.archive.ubuntu.com/ubuntu cosmic/main amd64 Packages
        100 /var/lib/dpkg/status
gnome-shell-common:
  Installed: 3.30.1-2ubuntu1
  Candidate: 3.30.1-2ubuntu1.18.10.1
  Version table:
     3.30.1-2ubuntu1.18.10.1 500
        500 http://ch.archive.ubuntu.com/ubuntu cosmic-updates/main amd64 Packages
        500 http://ch.archive.ubuntu.com/ubuntu cosmic-updates/main i386 Packages
 *** 3.30.1-2ubuntu1 500
        500 http://ch.archive.ubuntu.com/ubuntu cosmic/main amd64 Packages
        500 http://ch.archive.ubuntu.com/ubuntu cosmic/main i386 Packages
        100 /var/lib/dpkg/status

[Daniel van Vugt (vanvugt)]

Christian,

Please:

 1. Reproduce the login failure and then immediately after:

 2. Reboot

 3. Log into a VT and then run:

    journalctl -b-1 > preboot.txt

 4. Attach the file 'prevboot.txt' here.

[Christian Sarrasin (sxc731)]

Hi Daniel, please see attached; apologies for delay. I hope the weird "gnome-session-binary[4266]: CRITICAL: We failed, but the fail whale is dead. Sorry...." is a tell-tale sign?

Cheers
Christian

[Daniel van Vugt (vanvugt)]

Yes it appears the crash is:

Dec 25 15:18:52 x1c5 gnome-session[3657]: gnome-session-binary[3657]: WARNING: App 'org.gnome.Shell.desktop' exited with code 1
Dec 25 15:18:52 x1c5 gnome-session-binary[3657]: WARNING: App 'org.gnome.Shell.desktop' exited with cod

which looks likely to be caused by:

Dec 25 15:18:52 x1c5 gnome-shell[3813]: JS ERROR: Error: No valid stylesheet found for 'Yaru/gnome-shell.css'
                                        loadTheme@resource:///org/gnome/shell/ui/main.js:358:15
                                        _loadDefaultStylesheet@resource:///org/gnome/shell/ui/main.js:306:5
                                        _initializeUI@resource:///org/gnome/shell/ui/main.js:160:5
                                        start@resource:///org/gnome/shell/ui/main.js:136:5
                                        @<main>:1:31
Dec 25 15:18:52 x1c5 gnome-shell[3813]: Execution of main.js threw exception: Script <main> threw an exception

So yes it does sound like a theming problem. My only suggestion right now is to find a way to reset/reinstall any theme-related changes you have made. That might fix it but it won't tell us exactly what kind of change caused the problem :(

[Daniel van Vugt (vanvugt)]

Although it's pretty clear that the trigger for this bug is one of these changes:

https://launchpad.net/ubuntu/+source/gnome-shell/3.30.1-2ubuntu1.18.10.1

Had you made any theme changes other than using Pop? Did you install it manually or did it come with your machine?

[Christian Sarrasin (sxc731)]

Hi Daniel,

Thanks to the pointer. I now have 3.30.1-2ubuntu1.18.10.2 and it seems the issue is resolved (not sure if this is the new version or the manual fix below, which I applied thanks to your pointer).

I'd installed the Pop theme manually (through apt) atop stock 18.10. The slightly unorthodox thing I'd done was a soft-link from /usr/share/gnome-shell/theme/Yaru/gnome-shell.css onto ../gnome-shell.css, which is itself a soft-link to /usr/share/themes/Pop/gnome-shell/gnome-shell.css This would consistent theming of the lock screen, which doesn't appear to obey the control panel setting. Using the soft-links also makes it easier to spot when those files get overwritten by updates.

So it looks like the changes introduced in 3.30.1-2ubuntu1.18.10.1 makes it impossible to follow symlinks from /usr/share/gnome-shell/theme/Yaru/gnome-shell.css ? I guess it's perhaps debatable whether the standard gnome-shell package should reference a hardcoded theme (or maybe that's a GNOME limitation?)

Anyway, since I've worked around this issue, I guess this bug can be closed.

[Daniel van Vugt (vanvugt)]

I agree the hardcoded theme is not ideal. Regardless, bug closed.

[Anthony Chen (slightlyskepticalpotat)]

Sorry, I am new to using launchpad and marked it the status incorrectly.