IPP driverless printing

[Roman Riabenko via <help-guix@gnu.org>]

Hello

I am trying to print a test page in GNOME Settings on an IPP printer.
The printer automatically shows up in the printers panel. But clicking
the test print button does nothing. This works on nother distribution.
Do I need to configure something for driverless printing?

Printing was selected during Guix System graphical installation.

$ grep cups /etc/config.scm
(use-service-modules cups desktop networking ssh xorg
                 (service cups-service-type)

$ tail /var/log/cups/access_log -n  3
localhost - - [05/Jan/2025:15:42:53 +0200] "POST / HTTP/1.1" 200 345 Create-Printer-Subscriptions client-error-not-possible
localhost - - [05/Jan/2025:15:42:53 +0200] "POST / HTTP/1.1" 200 711358 CUPS-Get-PPDs -
localhost - - [05/Jan/2025:15:43:03 +0200] "POST / HTTP/1.1" 200 153 Cancel-Subscription client-error-not-found

$ tail /var/log/cups/error_log -n  5
I [05/Jan/2025:15:42:53 +0200] [Client 28] Started "/gnu/store/bp2x2hd9f8d7mqc9d1h5qa0nn4pfgqvs-cups-server-bin/lib/cups/daemon/cups-driverd" (pid=6455, file=14)
E [05/Jan/2025:15:42:53 +0200] [Client 29] Returning IPP client-error-not-possible for Create-Printer-Subscriptions (/) from localhost.
I [05/Jan/2025:15:42:53 +0200] [cups-driverd] Read \"/var/cache/cups/ppds.dat\", 1614 PPDs...
I [05/Jan/2025:15:42:53 +0200] [cups-driverd] No new or changed PPDs...
E [05/Jan/2025:15:42:55 +0200] [CGI] ippfind (PID 6458) stopped with status 3!

I also cannot open the Print Settings, but it is already tracked in a
report and seems to be unrelated: https://issues.guix.gnu.org/70491

$ grep Exec /run/current-system/profile/share/applications/system-config-printer.desktop
Exec=/gnu/store/pqdxjxcfrmvnl51qpdran5k7nbdvcf9l-system-config-printer-1.5.16/bin/system-config-printer
$ /gnu/store/pqdxjxcfrmvnl51qpdran5k7nbdvcf9l-system-config-printer-1.5.16/bin/system-config-printer
Traceback (most recent call last):
  File "/gnu/store/pqdxjxcfrmvnl51qpdran5k7nbdvcf9l-system-config-printer-1.5.16/share/system-config-printer/system-config-printer.py", line 76, in <module>
    import cupshelpers
ModuleNotFoundError: No module named 'cupshelpers'

Roman