Auto-discovered network driverless printer keeps being "rediscovered"

[hk21702]

Describe the bug
My network driverless printer keeps being added and removed occasionally without an obvious trigger, resulting in a spam of GNOME notifications. This occurs even if I add the printer manually (it simply duplicates it, similar to what's described in #1531).

Canon_MF642C_643C_644C_d9_9d_eb_d9_9d_eb_6_d9_9d_eb_4 is the misbehaving printer.
MF642C-643C-644C is the same printer, but added manually. It is behaving correctly, and the bad behavior of the discovered printer occurs even without this.

$ lpstat -t
scheduler is running
system default destination: MF642C-643C-644C
device for Canon_MF642C_643C_644C_d9_9d_eb_d9_9d_eb_6_d9_9d_eb_4: ipps://Canoncb6ba6.local:10443/ipp/print
device for MF642C-643C-644C: dnssd://Canon%20MF642C%2F643C%2F644C%20(d9%3A9d%3Aeb)%20(d9%3A9d%3Aeb)%20(6)%20(d9%3A9d%3Aeb)%20(4)._ipp._tcp.local/?uuid=6d4ff0ce-6b11-11d8-8020-f4a997cb6ba6
Canon_MF642C_643C_644C_d9_9d_eb_d9_9d_eb_6_d9_9d_eb_4 accepting requests since Mon 22 Jun 2026 12:28:31 PM EDT
MF642C-643C-644C accepting requests since Wed 06 May 2026 02:49:05 PM EDT
printer Canon_MF642C_643C_644C_d9_9d_eb_d9_9d_eb_6_d9_9d_eb_4 is idle.  enabled since Mon 22 Jun 2026 12:28:31 PM EDT
printer MF642C-643C-644C is idle.  enabled since Wed 06 May 2026 02:49:05 PM EDT

$lpstat -e
lpstat -e
Canon_MF642C_643C_644C_d9_9d_eb_d9_9d_eb_6_d9_9d_eb_4
MF642C-643C-644C

$sudo lpstat -e
Canon_MF642C_643C_644C_d9_9d_eb_d9_9d_eb_6_d9_9d_eb_4
MF642C-643C-644C

error_log.txt and attr.log

To Reproduce

Have a Canon MF642C 643C be discoverable on the network (I unfortunately don't have another printer to check if this behavior occurs with other printers) and wait.

Expected behavior

The printer is discovered once and not re-added over and over despite no change in state. Or at the very least, the printer is rediscovered silently.

Screenshots

GNOME notification spam

System Information:

• OS and its version: Ubuntu 26.04
• Application: N/A
• CUPS version: 2.4.16-1ubuntu1.3 (deb), 2.4.19-2 (snap)

Additional context

I've reported this downstream to Launchpad #2150560 already.

Disabling cups-browsed and also setting Browsing No in /etc/cups/cupsd.conf doesn't resolve the issue.

My best guess, given that the manually added printer seems fine, is that the auto-discovered printer keeps getting picked up in a cleanup loop, and then it subsequently gets rediscovered as a "new printer".

[michaelrsweet]

I've found that the CUPS snap will keep trying to add printers regardless of what the CUPS packages are configured to do. I just removed the CUPS snap entirely - give that a try as Ubuntu has this "run local cupsd and cupsd in a snap" hybrid arrangement...