No GUI error reason for when 'Clear All' button for printer jobs doesn't work

[Ads20000]

The Clear All button for clearing printer jobs doesn't work and no explanation is given (via a dialogue box etc) with why. Am trying to print to a Pixma MP 230 via USB, this isn't a bug to report that that's apparently not working, but a bug to state that no reason is given in the GUI for why Clear All doesn't work. A reason should be given so that the user can take action?

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-control-center 1:3.28.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-23.25-generic 4.15.18
Uname: Linux 4.15.0-23-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CurrentDesktop: communitheme:ubuntu:GNOME
Date: Mon Jun 18 22:43:51 2018
InstallationDate: Installed on 2017-08-03 (319 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: gnome-control-center
UpgradeStatus: Upgraded to bionic on 2018-04-22 (57 days ago)

[Ads20000 (ads20000)]

The denial is

```
Jun 18 22:51:10 adam-thinkpad-t430 kernel: audit: type=1400 audit(1529358670.977:81300): apparmor="DENIED" operation="capable" profile="/usr/sbin/cupsd" pid=2925 comm="cupsd" capability=12 capname="net_admin"
```

Can a good GUI error be given for errors like that?

[Sebastien Bacher (seb128)]

Thank you for your bug report. Is that option always failing?

Till, do you know avbout that apparmor denial?

[Till Kamppeter (till-kamppeter)]

Does the command line equivalent

cancel -a

work?

Does the "Clear All" button work after

aa-complain cupsd

[Till Kamppeter (till-kamppeter)]

Please also attach your file

/etc/apparmor.d/usr.sbin.cupsd