Closing, as we won't use grsec anymore.

This is fixed now, ensure your packagekit package is up-to-date.

I updated my system today, and Thunderbird now works normally.

That is impossible, since that would mean we need to downgrade our kernel, which we can't (ever) do.
Fortunately, this bug is easy to fix, now that we know the cause.

Thanks you @mak ! :)

Can we build our PureOS iso with the old udev udebs for now, as a workaround?

This should be resolved now, if you have version 0.3 of the pureos-gnome-settings package installed.
I still have to verify that this works with an actual Librem though.

Okay, done - with the next batch of updates, you should have a lot less wallpapers ;-)

We know the culprit now. As expected, it's in udev: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=872598

Beautiful! Well done @mak ! :)

So feel free to close this one here as it will come in from Debian soon :)

Hm, weird bug - can you reproduce it?

This is resolved with xdg-user-dirs 0.15-3, which should be available in PureOS in a few hours as well.

Fix released to Debian as version 0.9.7-3: https://tracker.debian.org/news/863564

I've sent a patch upstream, and will apply a fix in the Debian (and thereby PureOS package) after some brief discussion with the GNOME team, since the patch we mean we need to change the startup method away from Xsession.d startup entirely, and I am not sure if that breaks anything (I would say no, but there might be some weird corner case or DE I don't know).

Okay, the initial Debian bug that KiBi fixed was not the one we had in PureOS, but the exact same bug is affecting Debian now.
This issue is highly unstable in when it shows, but is at least reproducible with the same configuration of packages. Cyril is trying for find the cause of the problem by bisecting with Debian snapshots, and I am more randomly poking it to maybe find the cause of this issue.

This is this bug: https://bugs.mageia.org/show_bug.cgi?id=20882
Should be fixed soonish in Debian and PureOS.

I updated my system today, and Thunderbird now works normally.

Yes, GNOME Software requires an internet connection on its first run, and display a "please wait" message while it is refreshing. If none is there, I don't know exactly what happens, but I guess the SC being empty is the result.
There is no need to run apt update manually.