[cups] Issues with CUPS and AirPrint on iPadOS 16

[Jeff Dyck]

Hello all, 

I work for a school district that has about 4000-ish iPads and we use CUPS with a custom DNS domain setup to provide printing to these devices. I’m just now upgrading them to iPadOS 16, and discovered some kind of bug with printing to CUPS servers.

Up till now this setup has been working well, and with a combination of the AirPrint DNS records and the IPP-Everywhere communication our iPads have been able to print, select different paper sizes, even use most of the additional finishing options (staples, hole punch, etc) of our copiers.

Unfortunately, once the iPads move to iPadOS 16, a bunch of features in the print dialog simply disappear.  Specifically there is no longer any paper size option, nor are there any finishing options presented - the UI elements in the print dialog are simply gone.  I’ve done a bunch of testing and these features work fine when I point the iPad to a real AirPrint printer, they work fine if I’m on iOS 15, they work fine on MacOS as well.  I’m seeing the issue specifically with the combination of iPadOS 16 and a CUPS AirPrint queue, so I’m suspecting Apple may be parsing something slightly different? Maybe before they were more flexible but now being strict with specifications?

Wondering if anyone else has seen this or could confirm?  

I’ve made sure our DNS-SD entries match the Printer pretty much exactly to no difference, but if I compare the results of an IPP get-capabilities of the printer vs the CUPS queue there are quite a few differences.

Jeff