flatpak Thunderbird won't print to printer that autoconfigured after launch

[hzulla]

Hi,

this happened on Ubuntu 22.04 with flatpak 1.14.0-2flatpak1~22.04.1 installed and Thunderbird 105.0.1 via flatpak.

My printer Epson ET4750 is connected to my computer via Ethernet and autoconfigured by Ubuntu's default printer settings via network discovery.

How to reproduce:

• turn the printer off prior to starting the computer.
• start the computer.
• open the Ubuntu settings dialog for the printer: No, there is no printer visible to the system.
• launch flatpak-Thunderbird.
• turn on the printer after launching Thunderbird.
• open the Ubuntu settings dialog for the printer: Yes, the printer is now visible to the system and was autoconfigured.
• try to print an email or document from within Thunderbird.
• Thunderbird's internal print dialog will only offer "save as pdf".
• click Thunderbird's option to use the system's print dialog.
• system's print dialog when launched from Thunderbird also doesn't show the printer.
• now save the document as PDF.
• open Nautilus file explorer.
• click the PDF file and use the (non-flatpak) PDF viewer to open the document.
• print from within the PDF viewer application: I can now print to the printer.
• try again to print from withing Thunderbird: the printer is still not visible there.
• exit Thunderbird and restart it.
• now the printer also appears in Thunderbird's internal print dialog.

Expected behaviour:

• Thunderbird should be able to print to a printer once it is visible and configured by the system, even if that was done after launch.

[Erick555]

I guess /run/cups/cups.sock doesn't exist on your system if you didn't configure printer. If it's the case the it's unfixable on flatpak side. You need to ensure this path exist on startup - I think systemd socket activation may help here.