hplip-printer-app hangs and oddities (Re: Cups automatic duplex printing problems)

Hi list,

Dougs mention of the Snap repo helped somewhat but also broke somewhat more.

- I tried using the Snap backend, which seemed to help, a 2 sided print 
comes out 2 sided and a 2 copy 2 sided print comes out in 2 copies. (Or 
that is what I guessed from the remote printer display that tells me 
that the latter had 4 sides and printed out on 2 sheets of paper.) So 
far, so good.

- However. This makes things worse for my personal, unfortunately 
unbreakable, HP Laserjet 2055DN. I have installed the snap 
hplip-printer-app (edge) and added the printer, but it's printing raw 
Postscript every other time (%%@PJL ENTER LANGUAGE = Postscript 
%!PS-Adobe-3.0 %%LanguageLevel: 2).

Trying to use the pcl3 variant seems somewhat better but I've seen the 
weirdest messages in the logs. I even saw a 
"hplip-printer-app.hplip-printer-app-server[57930]: Segmentation fault 
(core dumped)" when I tried to remove a printer - maybe too soon, I'm 
not sure.

Also, removing jobs sometimes makes hplip-printer-app hang, i.e.  become 
totally non responsive; I've seen "hp[48675]: io/hpmud/jd.c 632: timeout 
write_channel hp:/net/HP_LaserJet_P2055dn?ip=172.17.2.55" that I don't 
understand and cannot get rid of, the Snap doesn't properly restart in 
these situations 
("snap.hplip-printer-app.hplip-printer-app-server.service: Killing 
process 54142 (hplip-printer-a) with signal SIGKILL.", "Failed with 
result 'timeout'" and "Unit process 54133 (hplip-printer-a) remains 
running after unit stopped."

I've also seen Evince snap hanging during getting printer information, 
but I'm not in the mood to yet have to debug _another_ printing problem.


Anyway, I'm guessing: the old way of printing doesn't work anymore for 
new printers but the new way of printing doesn't work for older printers 
yet? What should I do if I need the best of both worlds?


(Also: using the snap printing system makes Libreoffice forget all 
printers unless Libreoffice is a snap as well, but thats _even_ lower on 
the todo list than the Evince problem - and probably even off topic 
here, too).

Best regards,

Valentijn

On 31-01-2024 12:38, Douglas Kosovic wrote:
> Hi Valentijn,
[...]
> You could then try the official OpenPrinting Snap of CUPS for a much newer version of CUPS that has many bug fixes:
> https://snapcraft.io/install/cups/ubuntu
> 
> I believe Ubuntu will be moving to the CUPS Snap for its printing system in a future release
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