After the OS is running for a while, it may trigger for a bug that caused pkexec (including any application that use it, including synaptic) to hang. This can only be recovered from relaunching OS or gnome-shell.
This is a screenshot that describe this situation:
xhost +si:localuser:root pkexec synaptic
I remember the same error in Manjaro with gnome 3.28, it disappeared in gnome 3.30. How do I backport the fix (if there is any) to Ubuntu 18.04?
UPDATE 1
these are my desktop environment:
$ export | grep XDG_SESS
declare -x XDG_SESSION_DESKTOP="ubuntu"
declare -x XDG_SESSION_ID="1"
declare -x XDG_SESSION_TYPE="x11"
... and synaptics version
$ apt-cache policy synaptic
synaptic:
Installed: 0.84.3ubuntu1
Candidate: 0.84.3ubuntu1
Version table:
*** 0.84.3ubuntu1 500
500 http://archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
100 /var/lib/dpkg/status
peng@peng-ThinkPad-P51s:~$
UPDATE 2: it appears that it is caused by an unknown bug in gnome authentication agent, as I switched to XFCE and this problem never happens again, so now the problem becomes: how to get rid of the gnome authentication agent?
