Re: [cups] No destination host name supplied by cups-browsed for printer

Hi,

what is your minor version of CentOS? There was a bug within
cups-filters at earlier versions than 7.9 - CentOS 7.9 brought in some
fixes, so you can check.

Basically this error is produced by implicitclass backend when it is
unable to acquire the real destination for the print job.

The process (IIUC) is designed like this - cupsd creates a print job
when you try to print, spawning filters+implicitclass backend and cups
dbus notifier sends a dbus message (not exactly, but to keep it simple)
'There is a print job XY for print queue AB.'.

cups-browsed is set to listen to the message and updates the queue with
the real destination.

In meantime, implicitclass backend waits for the real destination with a
timeout, and if the real destination isn't available in time (f.e.
cups-browsed is busy, CUPS dbus notifier is slow), the it fails with the
mentioned message.

There was a GSoC project to make cups-browsed more efficient and
multi-threaded to prevent situations when cups-browsed is busy, but I'm
not sure what is the current status of the project, I only saw the
student passed the final evaluation.

On 10/7/20 2:54 PM, Patrick Bégou wrote:
> The solution is to manually restart cups service. However, the user has
> no root access on his laptop (it is not allowed in our professional
> environment) so the only work-around would be a cron task to restart cups ?
What always helped was to cancel any jobs (if there are in the queue)
with cancel -a, then remove the queue via lpadmin -x and restarting
cups-browsed. But I'm not sure what can be done without root access, but
I'm able to do this stuff even when I'm a member of wheel group.
>
> Did someone encounter this behavior and found the solution ? Could it be
> related to swiching from Wifi (at home) to wired network (at workplace)?
Yep, that is one case when it can happen. Other was hibernating the PC.
Neither of them I wasn't able to reproduce on stable basis.
>
> I have several laptops, all installed with the same kickstart file via
> PXE boot and cups running fine. All are DELL computers except this one
> which is a HP ZBook.
>
> Thanks for your help.
>
> Patrick
>
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-- 
Zdenek Dohnal
Software Engineer
Red Hat Czech - Brno TPB-C

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