Ubuntu
gnome-shell package

  1. Bug #1734095
  2. Comment #9

Comment 9 for bug 1734095

Revision history for this message
Luis (perdigao) wrote : Re: After upgrade to ubuntu 17.10 Software & Updates not showing authorization popup [gnome-shell[N]: pushModal: invocation of begin_modal failed]

I seem to have found a solution. Install polkit, in my case
sudo apt install lxpolkit

And then, it may be useful to check the Default applications in Menu -> Preferences -> Default applications for LXSession , select Core Applications , and make sure 'Polkit Agent' is set to lxpolkit.

Is it possible that in the default installation of ubuntu, the polkit package is not being installed by default?