[cups] LaserJet stopped working

[Ken Wright]

On Thu, 2023-04-13 at 15:04 +0200, Jörg Thümmler wrote:
> Am 13.04.23 um 13:49 schrieb Ken Wright:
> > On Thu, 2023-04-13 at 07:22 +0200, Jörg Thümmler wrote:
> > > Am 13.04.23 um 04:15 schrieb Ken Wright:
> > > > On Tue, 2023-04-11 at 09:13 +0200, Jörg Thümmler wrote:
> > > > > Hi,
> > > > > 
> > > > > have a look at the print system of the laptop... if it's
> > > > > linux & cups, look at localhost:631 and "printers". Cups
> > > > > stops print queues when errors occure by default.

> > > > > Same may be, if your laptop runs on windows, have a look at
> > > > > the "settings/devices/printers/<yourprinter>" ... if it is
> > > > > "offline" means connection to the cups server is somehow
> > > > > lost.
> > > > > 
> > > > > Also check the cups on the server, same thing, queue may be
> > > > > stopped.
> > > > 
> > > > Now here's an interesting datum:  I can print from the server's
> > > > command line using the lp command, but when I try to print a
> > > > test page from CUPS (2.4.2, if that helps) nothing prints.  The
> > > > print job shows "connecting to printer" then goes away, as
> > > > though the printing had finished.  I suspect this may be
> > > > related to the reason I can't print from my Ubuntu laptop.
> > > 
> > > Hi,
> > > 
> > > do you use the same printer queue in both cases?
> > > 
> > Yes.
> 
> Hi,
> 
> the document you can print by "lp" command is pdf or ps type as the
> cups testpage is?

It was just a text file.  A .conf file from nginx.

> can you show your working "lp" commandline?

lp /etc/nginx/conf.d/duplicati.conf

> I can only remember one situation like this, there cups correctly was
> sending the jobs , but the printer didn't understand the printfile 
> format. So the files "vanished" in cups (found then in the "finished"
> folder). The printer began to load the job (LED flashing) and shortly
> after that stopped flashing and that was all.

After I read this, I copied a one-page .pdf to the server and tried
printing it, along with another plain text file.  Neither worked until
I rebooted the server, after which they printed immediately.  Still
can't print the test page from CUPS, though.