Backend /usr/lib/cups/backend/cups-pdf does not exist

After running diagnostics in CUPS here is the output

D [02/May/2010:09:46:45 -0400] cupsdSetBusyState: Dirty files
D [02/May/2010:09:46:45 -0400] cupsdReadClient: 12 POST / HTTP/1.1
D [02/May/2010:09:46:45 -0400] cupsdSetBusyState: Active clients and dirty files
D [02/May/2010:09:46:45 -0400] cupsdAuthorize: No authentication data provided.
D [02/May/2010:09:46:45 -0400] cupsdReadClient: 12 1.1 Get-Jobs 1
D [02/May/2010:09:46:45 -0400] Get-Jobs ipp://localhost/printers/
D [02/May/2010:09:46:45 -0400] [Job 2947] Loading attributes...
D [02/May/2010:09:46:45 -0400] Returning IPP successful-ok for Get-Jobs (ipp://localhost/printers/) from localhost
D [02/May/2010:09:46:45 -0400] cupsdSetBusyState: Dirty files
D [02/May/2010:09:46:45 -0400] cupsdReadClient: 12 POST / HTTP/1.1
D [02/May/2010:09:46:45 -0400] cupsdSetBusyState: Active clients and dirty files
D [02/May/2010:09:46:45 -0400] cupsdAuthorize: No authentication data provided.
D [02/May/2010:09:46:45 -0400] cupsdReadClient: 12 1.1 Get-Jobs 1
D [02/May/2010:09:46:45 -0400] Get-Jobs ipp://localhost/printers/
D [02/May/2010:09:46:45 -0400] [Job 2449] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2450] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2451] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2452] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2453] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2454] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2455] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2456] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2457] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2458] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2459] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2460] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2461] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2462] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2463] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2464] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2465] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2466] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2467] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2468] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2469] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2470] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2471] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2472] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2473] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2474] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2475] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2476] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2477] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2478] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2479] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2480] Loading attributes...
D [02/May/2010:09:46:45 -0400] [Job 2481] Loading attributes...
D [02/May/2...

I solved this issue by purging then reinstalling cups-pdf.

Then when adding a PDF printer I noticed the cups printername must be at least 4 characters (if not APPLY is greyed out). My cups-pdf printer on Karmic only had 3 chars ('PDF') - maybe the issue is related to that?

I can confirm that I see this on a 8.04.2 LTS -> 10.04 LTS upgraded box on a print queue called PDF.

I can confirm this also on an upgrade from 8.04 LTS to 10.04 LTS. I (re)installed cups-pdf without effect. However I noticed that the printer was not enabled in Printer Properties under Polices. I checked the box and all was well once again.

I experienced this on Maverick (10.10) after upgrading from Lucid (10.04).

To fix, I did the following:
1) sudo aptitude purge cups-pdf
2) sudo aptitude install cups-pdf
3) Right click on printer -> Properties -> Policies -> check "Enabled".
4) Click "Apply".

Is the cups-pdf package even installed, when that message appears?

> Is the cups-pdf package even installed, when that message appears?

Yes, I was using it without problems before upgrading.

What I don't get is, why the hell CUPS would say that the back-end isn't there, when it is, instead of simply reporting that, from now on, queue names should have at least 4 characters, if that is what the real issue is all about?

I have printer names with only 1 (one) character and they work, so CUPS allows queue names shorter than 4 characters.

If a printer setup tool requires you to enter at least for characters for a new print queue, report a bug in that printer setup tool.

Note also that in system-config-printer the "Forward" button is grayed out if the name in the field equals the name of an already existing queue.

Now that I remember, cups-pdf was removed in the upgrade. Just to make sure I remembered this correctly, I did a search, and found this:
http://kubuntuforums.net/forums/index.php?topic=3114263.0

"The cups-pdf package is removed as obsolete in the upgrade to Maverick, breaking the PDF printer by removing the backend but not the printer installation, which has to be removed manually."

This would explain why a purge & reinstall would work. Does anyone know why it would be considered obsolete? I think that's the real error here, unless there's some new alternative that we don't know about.

On Fri, Nov 19, 2010 at 7:12 AM, Colan Schwartz wrote:
> Now that I remember, cups-pdf was removed in the upgrade.  Just to make sure I remembered this correctly, I did a search, and found this:
> http://kubuntuforums.net/forums/index.php?topic=3114263.0
>
> "The cups-pdf package is removed as obsolete in the upgrade to Maverick,
> breaking the PDF printer by removing the backend but not the printer
> installation, which has to be removed manually."
>
> This would explain why a purge & reinstall would work.  Does anyone know
> why it would be considered obsolete?  I think that's the real error
> here, unless there's some new alternative that we don't know about.

Because ever since GTK and QT acquired the ability to save to PDF via
their printing dialog, the need for a network-oriented PDF printer has
been greatly reduced. This being said, the GTK implementation is so
pitiful that I hardly ever use it.

Thank you for taking the time to report this bug. Could you please test this against the current version of "cups-pdf" found in my Personal Package Archive (PPA) at https://launchpad.net/~q-funk/+archive/ppa and confirm whether the issue still applies?

I just allowed a "distribution upgrade" that kind of wasn't - Similar to that described here http://ubuntuforums.org/showthread.php?t=1675140
Anyway it asked me if I wanted to remove cups-pdf because it was obsolete and I said NO KEEP IT, it's much better than the GTK save as PDF function.

Just tried to test your package archive but got this message after I added it to /etc/apt/sources.list
--------------
"Failed to fetch https://launchpad.net/~q-funk/+archive/ppa/dists/lucid/main/binary-i386/Packages.gz The requested URL returned error: 404
Some index files failed to download, they have been ignored, or old ones used instead."
--------------

The line I added was "deb https://launchpad.net/~q-funk/+archive/ppa lucid main"

The correct line would be:

deb http://ppa.launchpad.net/q-funk/ppa/ubuntu lucid main

This bug was fixed in the package cups-pdf - 2.5.1-2

---------------
cups-pdf (2.5.1-2) unstable; urgency=low

  * Refreshed our config patch to reduce the diff with upstream to a minimum.
  * Implemented a CUPS queue purging loop in [postrm] to remove all traces of
    CUPS-PDF in the CUPS configuration after a package purge. (LP: #573667)
 -- Martin-Eric Racine <email address hidden> Wed, 16 Mar 2011 17:18:00 +0200

I've added lucid and maverick tasks to this bug to match the uploads in lucid- and maverick-proposed. However, both of those packages seem to have unrelated changes. The changelog also doesn't need to mention all the other unrelated changes - particularly those which were reverted by subsequent Debian uploads.

Please re-upload without the unrelated changes. Thanks!

Please see 805947 for the complete fix for Lucid and Maverick.

Accepted cups-pdf into lucid-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

Accepted cups-pdf into maverick-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

Hello AllenWeber, or anyone else affected,

Accepted cups-pdf into lucid-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

Hello AllenWeber, or anyone else affected,

Accepted cups-pdf into maverick-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

Where is the test case for the SRU?

Rolf, AllenWeber, to verify this SRU on a Lucid or Maverick box install the proposed package and check for the presence of cups-pdf print queues by entering in a terminal window

lpstat -v | grep cups-pdf:

There should be at least one, most probably named "PDF". Now uninstall cups-pdf with the command

sudo dpkg -P cups-pdf

and run

lpstat -v | grep cups-pdf:

again. Now there should be no cups-pdf queue at all. Is this the case? Then the proposed package fixes this bug.

Till, thank you for the instructions. However, I like to do before-and-after testing. Making sure that I am indeed affected before installing the package from -proposed. I'm not sure I fully understand the issue here, but I don't think I'm affected and as such would think the current package as-is is fine. I need more information to reproduce. FWIW, cups-pdf package is installed. But apart from the "Print to file" option, I see no PDF printer (the one printing to ~/PDF, I assume).

Rolf, the problem described in this bug report is that when uninstalling (purging) the cups-pdf package, the existing cups-pdf CUPS queues are not removed and stray non-functional, as they need the CUPS backend which comes with the cups-pdf package. The proposed fix is a correction in the postrm script of the package so that the queues are actually removed.

For before-and-after testing, uninstall the cups-pdf package before updating and check whether the cups-pdf queues go away. Then install the new cups-pdf package (which auto-creates one queue, but you can add more for your testing) and then uninstall the new package again. Check again whether the cups-pdf queues go away.

To determine whether you have cups-pdf queues or not, run the command

lpstat -v | grep cups-pdf:

as described in comment #23.

Till, thank you for the patient explanation. I was now able to verify both the problem in this ticket and the fix from -proposed.

I tested Lucid only

Is bug 805947 blocking release of this package to lucid-updates (c.f. http://people.canonical.com/~ubuntu-archive/pending-sru.html)? As stated in that ticket this should not happen.

This bug was fixed in the package cups-pdf - 2.5.0-17ubuntu1~lucid1

---------------
cups-pdf (2.5.0-17ubuntu1~lucid1) lucid-proposed; urgency=low

  * Maintenance release to the 2.5.0 branch for Ubuntu Lucid and Maverick.
    Backports many maintainer script features to foolproof the installation
    and removal processes, per feedback from Martin Pitt and Till Kamppeter.
  * Hand-picked fixes from 2.5.1-5 and 2.5.1-7 packaging:
    + Modified the force-reload loop in [postinst|prerm|postrm] to end with ||:
      rather than with ||true for consistency with other maintainer commands.
    + Added a wait loop in [postinst|prerm|postrm] to ensure that CUPS reloaded.
    + Added 'cupsenable' and 'cupsaccept' steps in [postinst] to ensure that
      the PDF queue is up and running before we can manipulate it. (LP: #805947)
    + Added 'cupsdisable' and 'cupsreject' steps in [prerm|postrm] to match.
  * Hand-picked fixes from 2.5.1-3 packaging:
    + Remove the superfluous -E option to the queue creation loop in [postinst].
      This was unnecessary to access localhost plus it sometimes makes automated
      installs fail. (Closes: #614713,#539156).
    + Implemented a CUPS queue purging loop in [postrm] to remove all traces of
      CUPS-PDF in the CUPS configuration after a package purge. (LP: #573667)
    + Enforced -h localhost usage in [prerm] for [postinst/postrm] consistency.
    + Bumped Standards-Version to 3.9.2 (no change required).
  * Reverted LFS support from 2.5.0-17 in [debian/rules] since it never made it
    to any stable distro. It remains in the 2.5.1 branch for those who need it.
 -- Martin-Eric Racine <email address hidden> Sun, 25 Sep 2011 13:58:30 +0300

This bug was fixed in the package cups-pdf - 2.5.0-17ubuntu1~maverick1

---------------
cups-pdf (2.5.0-17ubuntu1~maverick1) maverick-proposed; urgency=low

  * Maintenance release to the 2.5.0 branch for Ubuntu Lucid and Maverick.
    Backports many maintainer script features to foolproof the installation
    and removal processes, per feedback from Martin Pitt and Till Kamppeter.
  * Hand-picked fixes from 2.5.1-5 and 2.5.1-7 packaging:
    + Modified the force-reload loop in [postinst|prerm|postrm] to end with ||:
      rather than with ||true for consistency with other maintainer commands.
    + Added a wait loop in [postinst|prerm|postrm] to ensure that CUPS reloaded.
    + Added 'cupsenable' and 'cupsaccept' steps in [postinst] to ensure that
      the PDF queue is up and running before we can manipulate it. (LP: #805947)
    + Added 'cupsdisable' and 'cupsreject' steps in [prerm|postrm] to match.
  * Hand-picked fixes from 2.5.1-3 packaging:
    + Remove the superfluous -E option to the queue creation loop in [postinst].
      This was unnecessary to access localhost plus it sometimes makes automated
      installs fail. (Closes: #614713,#539156).
    + Implemented a CUPS queue purging loop in [postrm] to remove all traces of
      CUPS-PDF in the CUPS configuration after a package purge. (LP: #573667)
    + Enforced -h localhost usage in [prerm] for [postinst/postrm] consistency.
    + Bumped Standards-Version to 3.9.2 (no change required).
  * Reverted LFS support from 2.5.0-17 in [debian/rules] since it never made it
    to any stable distro. It remains in the 2.5.1 branch for those who need it.
 -- Martin-Eric Racine <email address hidden> Sun, 25 Sep 2011 13:58:30 +0300