Cannot add a printer with KDE System Setting

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#1

I installed Tumbleweed a few days ago.
I have been using Kubuntu and Fedora to connect to my printer and KDE System Setting. I never encountered any problems.
But now, when I open KDE System Setting in the same way and click Add printer, I get “Failed to get a list of devices: ‘Forbidden’” (I am using the Japanese version, so the expression may be slightly incorrect. However, it does indeed say “Forbidden.”) The error message “Failed to get a list of devices: ‘Forbidden’” is displayed.
I found a similar error in Ask Ubuntu (permissions - "Failed to get a list of devices: 'Forbidden'", when list new printers on Kubuntu20.04 - Ask Ubuntu), but it seems to be managed by root in openSUSE, so it did not help. That is, in /etc/cups/cups-files.conf it says this.

# Administrator user group, used to match @SYSTEM in cupsd.conf policy rules...
# This cannot contain the Group value for security reasons...
SystemGroup root

Also, I checked the previous post on this form, which stated that it was because I was authenticating with my account instead of Root(Can't add printer in KDE System Settings), but I was authenticating with Root.
I had authenticated with Root. When I intentionally entered the wrong password, I was scolded for “Wrong Password”, so at least it seems to be authenticated correctly as Root.

I ran sudo journalctl -u cups.service and checked the logs and got the following results.

 7月 17 21:28:25 localhost.localdomain cupsd[1417]: pam_kwallet5(cups:auth): pam_kwallet5: pam_sm_authenticate
 7月 17 21:28:25 localhost.localdomain cupsd[1417]: pam_kwallet5(cups:auth): pam_kwallet5: Refusing to do anything for the root user
 7月 17 21:28:25 localhost.localdomain cupsd[1417]: pam_kwallet5(cups:setcred): pam_kwallet5: pam_sm_setcred
 7月 17 21:28:25 localhost.localdomain cupsd[1417]: pam_kwallet5(cups:auth): pam_kwallet5: pam_sm_authenticate
 7月 17 21:28:25 localhost.localdomain cupsd[1417]: pam_kwallet5(cups:auth): pam_kwallet5: Refusing to do anything for the root user
 7月 17 21:28:25 localhost.localdomain cupsd[1417]: pam_kwallet5(cups:setcred): pam_kwallet5: pam_sm_setcred

Also, the result of sudo cat /var/log/cups/error_log is as follows.

E [17/Jul/2023:21:28:32 +0900] [Client 36] Returning HTTP Forbidden for CUPS-Get-Devices (no URI) from localhost
E [17/Jul/2023:21:28:48 +0900] [Client 44] Returning HTTP Forbidden for CUPS-Get-Devices (no URI) from localhost

Access from Root seems to be denied.
I do not know if this is a problem with kde system setting, cups, or something else.
What is the cause? Or is there a way to investigate the cause more deeply? I would be grateful if you could tell me.
Please forgive my poor English. Thank you.

*I posted this in another topic that was not very appropriate before, and it was moved, but I deleted it and reopened it because it was not well explained. I apologize for any inconvenience caused.

#2

I did an install of TW a few weeks ago and in order to configure my printer I had to log into KDE as root and install the package system-config-printer package. Then I was able to configure my printer and have TW detect it over the network.

#3

Also make sure the mdns service is allow on the firewall.

#4

The configuration app provided by that package seems to be working perfectly. The search also seems to be working.
Thanks to the firewall configuration, I can also configure it in the CUPS Web UI.
However, the problem with KDE System setting does not seem to be resolved.
This is despite the fact that I am authenticating as root, just like the other two.
Should I assume that it is a problem with the printer management part of the KDE System setting, or is it a problem with the setup if other people are using the same version?
For the time being, I would like to explore the KDE System setting issue while continuing to use system-config-printer.
Thanks for sharing a good tool with me.

#5

You’re still having an issue in KDE System Setting after installing system-config-printer and allowing mdns on the firewall? What error are you seeing?

For me I simply ran the following:

sudo zypper in system-config-printer
sudo firewall-cmd --add-service=mdns
sudo firewall-cmd --add-service=mdns --permanent

Then I logged out of my personal account and logged into KDE as root and I was able to add my printer thru the KDE System Settings.

If you are still having an issue please post the error so we can troubleshoot.

#6

Better use Yast - add printer or the
CUPS interface at localhost:631

The KDE interface would interfere with yast.

If you have a network printer and want automatic discovery in a home network, deactivate the firewall momentarily and you can find your network printers automatically.
Or you can try to open the cups ports in the firewall.

#7

Am I correct in assuming that you are logged in by typing root in the SDDM?
I had never tried it before, so I did, and it did indeed work. The printer management function itself seems to be working properly.
The printer management screen in KDE System Setting does not always ask for the Root password, and it seems to be different from the Root password prompt we are used to, so I am assuming that is where the problem lies.
I am relieved that it does not seem to be a setup problem. I’m afraid to log in to KDE as root every time, so I’ll just look for the corresponding problem in KDE’s bugzilla.
By the way, the screenshot shows the error screen encountered by a regular user. Can you see it in your environment?(After attaching it, I remembered that it is in Japanese. The error is in the active window, in red.)

user
user1366×768 104 KB

#8

I didn’t know that. I’m used to it and I’m inclined to keep using it, but I’ll use yast and cups web ui.

#9

The KDE printer config utility, YaST printer config utility, system-config-printer, CUPS web interface, and CUPS lpadmin utility are all alternative means to the same end. None conflict with each other - they all act on the same system configuration files.

#10

When I install, I don’t see my network printer, but after adding the ipp-client to the zone in the firewall, the printer just shows up.

#11

The KDE printer-gui definitely inflicts on my headache for ages. So rule of thumb: don’t use it.

#12

What actual problems did you encounter?