Print settings present two distinct interfaces for adding printers

[Casey]

1. Running stock 18.04.1
2. gnome-control-center 3.28.2-0ubuntu0.18.04.2

As shown in the first screenshot below, the print settings panel shows an "Add..." in the headerbar as well as "Add a printer..." and "Additional printer settings" in the main area.

The first two buttons are highlighted and would naturally seem to be the first options to try, but they didn't actually work. While I was able to browse the list of printers attached to the print server, attempting to actually add the printer ended in an uninformative error message as shown in the second screenshot.

On the other hand, "Additional printer settings" launches the old system-config-printer utility which did succeed in adding my desired printer.

It is not at all obvious without trial and error which option one should choose to add a new printer.

[Sebastien Bacher (seb128)]

Thank you for your bug report, could you add your journalctl log/command line output after trying to add the printer and getting the error dialog?

The "additional printer settings" button is a temporary Ubuntu workaround until the upstream settings UI provide feature parity (e.g printer sharing)

[Casey (casey-jao)]

Sure.

[Sebastien Bacher (seb128)]

That's useful, what version of cups-pk-helper is installed (dpkg -l | grep cups-pk-helper)? It would be interesting to know if you have the fix from https://launchpad.net/ubuntu/+source/cups-pk-helper/0.2.6-1ubuntu1.2

[Casey (casey-jao)]

apt policy cups-pk-helper reveals

Installed: 0.2.6-1ubuntu1.2

[Sebastien Bacher (seb128)]

what's the output of "groups" for your user?

[Casey (casey-jao)]

groups:
casey adm cdrom sudo dip plugdev lpadmin sambashare lxd

[Sebastien Bacher (seb128)]

Thanks, that looks normal. I'm Ccing Till who looks after printing in Ubuntu, maybe he has an idea what could be wrong/why cups-pk-helper errors out. You didn't attach your journalctl log around the time of the error, could you do that, it could include clues

[Till Kamppeter (till-kamppeter)]

For cups-pk-helper problems we need appropriate log files, as Sebastien already asked for.

For the buttons, the "Additional printer settings" is not for adding printers but for getting into an advanced interface (system-config-printer). Perhaps one could rename it into "Advanced printer settings"?

The "Add a printer..." in the center of the screen only appears if there is no printer set up at all. The "Add" button at the top is always there, to be able to add more printers when there is already at least one set up. I do not know whether one could improve the design here. I would leave this to the GUI experts.

[Casey (casey-jao)]

Thanks for your followup.

journalctl | grep cups-pk-helper

yields exactly two entries from that day:

Nov 26 11:08:22 localhost.localdomain gnome-control-c[27707]: cups-pk-helper: addition of printer 1002 failed: client-error-not-authorized
Nov 26 16:33:53 localhost.localdomain gnome-control-c[7361]: cups-pk-helper: addition of printer 1002 failed: client-error-not-authorized

I can consistently reproduce this behavior. If I try to add another printer the same error results and yields the journalctl entry

Nov 30 07:41:32 localhost.localdomain gnome-control-c[13550]: cups-pk-helper: addition of printer 958_small failed: client-error-not-authorized

Is there a way to run cups-pk-helper in a verbose or debugging mode?

[Till Kamppeter (till-kamppeter)]

Is your user account in the lpadmin group in /etc/group (this is default for the first user created during installation)?

[Casey (casey-jao)]

Yes.

grep lpadmin /etc/group

lpadmin:x:116:casey

[Casey (casey-jao)]

So, the error "client-error-not-authorized" is from CUPS. Can someone shed light on that error?