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[0] - https://fedoraproject.org/wiki/How_to_debug_printing_problems
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Brandon Nielsen 2021-06-16 18:39:09 -05:00 committed by Zdenek Dohnal
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** xref:how-to-edit-iptables-rules.adoc[How to edit iptables rules] ** xref:how-to-edit-iptables-rules.adoc[How to edit iptables rules]
** xref:samba.adoc[How to create a Samba share] ** xref:samba.adoc[How to create a Samba share]
** xref:join-active-directory-freeipa.adoc[How to join an Active Directory or FreeIPA domain] ** xref:join-active-directory-freeipa.adoc[How to join an Active Directory or FreeIPA domain]
** NVIDIA ** NVIDIA
*** xref:bumblebee.adoc[NVIDIA Optimus Bumblebee] *** xref:bumblebee.adoc[NVIDIA Optimus Bumblebee]
*** xref:how-to-set-nvidia-as-primary-gpu-on-optimus-based-laptops.adoc[How to Set NVIDIA as Primary GPU on Optimus-based Laptops] *** xref:how-to-set-nvidia-as-primary-gpu-on-optimus-based-laptops.adoc[How to Set NVIDIA as Primary GPU on Optimus-based Laptops]
@ -102,5 +103,13 @@
** xref:installing-mysql-mariadb.adoc[Installing, Configuring and Troubleshooting MySql/MariaDB] ** xref:installing-mysql-mariadb.adoc[Installing, Configuring and Troubleshooting MySql/MariaDB]
** xref:manage-sql-server.adoc[How to Manage your SQL Server from GUI] ** xref:manage-sql-server.adoc[How to Manage your SQL Server from GUI]
* Printing and scanning
** xref:how-to-debug-printing-problems.adoc[Troubleshooting printing issues]
** xref:how-to-debug-scanning-problems.adoc[Troubleshooting scanning issues]
** xref:cups-useful-tricks.adoc[Useful tricks]
** xref:cups-terminology.adoc[Terminology]
** xref:cups-known-issues.adoc[Known issues]
** xref:cups-filing-a-bug-report.adoc[Filing a bug report]
* FAQ * FAQ
** xref:fedora-and-red-hat-enterprise-linux.adoc[Difference between Fedora and Red Hat Enterprise Linux] ** xref:fedora-and-red-hat-enterprise-linux.adoc[Difference between Fedora and Red Hat Enterprise Linux]

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[id='con_cups-known-issues']
= Known issues
Here are several known issues, which arise with certain circumstances, and there isn't general solution or upstream didn't want to add the solution to its project:
== cups-browsed
=== Cannot print due 'No destination hostname provided by cups-browsed, is it running?'
cups-browsed sometimes loses connection to print server (usually with old ones, like cups-1.4.2) when laptop changes network connection (change of WiFi network or after hibernate/suspend). You can make printing working again with cancelling your jobs and restarting cups-browsed by
----
$ cancel -a
$ sudo systemctl restart cups-browsed
----
=== cups-browsed consumes large amount of CPU
Creating local printer queues takes long time for some printers with larger PPD file, so timeout of http connection will time out and it creates infinite loop of creating local printer queues. To solve this issue, please add
----
HttpLocalTimeout N
HttpRemoteTimeout N
----
into [filename]`/etc/cups/cups-browsed.conf`, where `N` is number of seconds after which connection is timed out. Then restart cups-browsed service. This option is currently in Fedora 27 and above.
=== [SINCE FEDORA 27] cups-browsed creates different printer queue names than before
This issue is connected to remote cups queues, which are advertised by older CUPS version (usually below cups-1.5, e.g. RHEL 6). Cups-browsed creates local print queues named by printer's DNS-SD ID by default and naming by remote cups queue is enabled again by adding:
----
LocalQueueNamingRemoteCUPS RemoteName
----
into [filename]`/etc/cups/cups-browsed.conf` and restart cups-browsed service.
== cups-filters
=== Printing takes a long time or doesn't print at all
When your printer needs a lot of time to do printing (from your POV) or doesn't print at all (some Xerox printers have such problems with gs renderer, so they are working again only with pdftops renderer), you can try to change the default postscript renderer. The default renderer in Fedora for most printers is gs filter from Ghostscript, but we have pdftops filter from Poppler for Brother, Minolta and Konica Minolta printers - this setup is called hybrid.
Other available renderer setups are gs (from Ghostscript), pdftops and pdftocairo (from Poppler), mupdf (from mupdf) and acroread (from adobe reader, not in Fedora official repositories), then you can set different default renderer for your print queue like this:
----
# lpadmin -p <printer-name> -o pdftops-renderer-default=gs/pdftops/pdftocairo/mudpf/acroread/hybrid
----
*BEWARE:* Most 'slow' printing issues are caused by PDF creating applications, which generates bad PDF file - and that bad generated PDF file is mostly the core of problem. To sum it up, slow printing issue can rise again with different PDF file, then it is on user's decision: if he wants to print fast and probably sometimes change the default renderer, or slow printing is not such critical issue.
== CUPS
=== [Fixed in F33 and later] Firefox, Evince (PDF viewer), GVim, Gedit, Gnome Control Center show a 'dummy'/duplicate print queue, which doesn't work
This bug is connected to every application which uses GTK print dialog. GTK dialog decided to take information about available from two sources - mDNS messages from Avahi and CUPS - this dummy/duplicate print queue is a print queue GTK created in its dialog based on Avahi messages, but it doesn't exist in CUPS, because no one created it, and later GTK behaves like it exists in CUPS. So every time an user wants to print, GTK sends a request to CUPS for this queue, but it gets dropped by CUPS because the queue doesn't exist.
The feature which GTK is trying to do here is called CUPS temporary queues - GTK developers is currently working on a immediate fix in this https://bugzilla.redhat.com/show_bug.cgi?id=1784449[bugzilla]. The future plan is to use https://github.com/OpenPrinting/cpdb-backend-cups[cpdb-backend-cups] backend in GTK, but right now we are focusing on the intermediate fix.
=== CUPS doesn't take nicely some kinds of FQDN
CUPS sometimes has problems with some kinds of FQDN - that means when you use FQDN in [option]`BrowsePoll` directive in [filename]`/etc/cups/cups-browsed.conf`, CUPS doesn't recognize it as valid hostname - it is solved by adding:
----
ServerAlias your.own.fully.qualified.hostname.com
----
into [filename]`/etc/cups/client.conf` and restarting cups service.
== HPLIP
First I would like to mention that we are not responsible for support HPLIP, which is downloaded and installed from HP website. Please install hplip rpms from official Fedora repositories at most cases.
=== Hp-plugin: file does not match its checksum. File may have been corrupted or altered
This common error is mostly caused by external causes (server outage, network outage), when wget tries to download plugin, but it returns only error message. It is connected with message:
----
Plugin download failed with error code = N
----
where `N` is return value of [command]`wget` ([command]`man wget`), which is used for downloading proprietary plugin. Solutions for this issue may vary - you can wait until servers go up again or try to install plugin, which you download manually from http://www.openprinting.org/download/printdriver/auxfiles/HP/plugins/ (select "Select and install an existing local copy of the plug-in file" during [command]`hp-setup` or [command]`hp-plugin`).
=== Unable to load cupsext
This error can occur when hplip is installed from HP website, or its dependencies are mixed python2 and python3 packages or installed by pip. This is solved by removing all hplip packages (hplip, hplip-gui, hplip-libs, hplip-common, libsane-hpiao) and installing them again all from repositories.
=== Missing hplip-gui
GUI tools and GUI parts of HP commands are moved to hplip-gui subpackage, because the main package can work without GUI, so the main package is smaller. The outcome of this decision is HP commands need to be run with `-i` option for interactive mode, or hplip-gui subpackage needs to be installed.
Tools, which need to be run with `-i` option for CLI or need to have hplip-gui installed for GUI:
----
hp-align
hp-clean
hp-colorcal
hp-diagnose_queues
hp-fab
hp-firmware
hp-info
hp-plugin
hp-sendfax
hp-setup
hp-testpage
hp-unload
----
Tools, which are in hplip-gui:
----
hp-check
hp-print
hp-systray
hp-toolbox
hp-devicesettings
hp-faxsetup
hp-linefeedcal
hp-makecopies
hp-printsettings
hp-wificonfig
----
=== HP printer isn't discovered, doesn't print or doesn't print well
Some HP printers don't work well with URIs provided by CUPS (dnssd, usb, ipp) or they need proprietary plugin from HP, which cannot be in Fedora because of licensing issues. For such printers please try to run:
----
hp-setup -i -g
----
for interactive mode, or:
----
hp-setup -g
----
for graphic mode. This command installs HP printers and HP scanners. If you have issue about HP printer/HP scanner, which isn't discovered, doesn't print or doesn't print well, please try to install it by [command]`hp-setup`, if it helps. If it doesn't help, please file a bugzilla, attach output of hp-setup and mention that you tried [command]`hp-setup`.
=== Device which needs plugin does not work after HPLIP update
Devices which need plugin can stop to work after update to newer HPLIP version - it is due the check for plugin version in the code. The check is necessary to prevent inconsitencies when new features in open sourced HPLIP need new proprietary libraries from plugin. To make your printer work again, just download and install plugin again with:
----
$ hp-plugin -i
----
=== Devices which require a binary plugin stopped to work on Fedora Silverblue/CoreOS
Devices which require a HP close source binary plugin need to have plugin installed every time you start/restart your PC by default. HP closed source script installs the plugins into a readonly directories, so the plugins are removed once you start/restart Fedora. The workaround is to try if your device supports driverless printing and scanning, try hplip-plugin package from RPMFusion or keep installing the plugin everytime you want to print.
=== HP USB printer/scanner doesn't work due a conflict on USB port
HPLIP proprietary binary plugins tends to conflict on the USB port where HP device is connected, if the HP device is capable of using IPP over USB and if *ipp-usb* package is installed. The solution is to _remove hplip_ and have the device being maintained by *ipp-usb* and *sane-airscan*, because it provides newer open sourced protocols and you are not limited by problems caused by closed source plugins (needed to be reinstalled every time there is a new HPLIP version, they don't work stable on Silverblue/CoreOS).

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[id='con_cups-terminology-for-printing-and-scanning']
= Terminology for printing and scanning
== Printing
=== Print queue
Abstraction unit in CUPS for a printer - it has a device uri, which represents connection to the device, and can exist with classic driver (PPD file from different package) or without (driverless printing). The entries you see in print dialogs and settings are those _print queues_. They can be _permanent or temporary_.
=== Permanent print queues
The queues with classic driver or driverless print queue which need to be shared further down the network.
=== Temporary print queues
The queue which don't need to be installed at all - they show up during print dialog and they disappear once the printing is done successfully. They rely on _driverless printing_.
=== Remote CUPS queue
The queue on the different machine, where other cupsd process is running, than on the local machine. They are usually found in enterprise solutions, where printers aren't in the same network as users or if admin wants a centralized monitoring above all printers. In such solutions, users set up _cups-browsed_ to install remote CUPS queue as local queues via _BrowsePoll_ directive, or install a specific queue via GNOME. There can be a solution how to redirect mDNS messages which CUPS server advertises to the networks with users, but I haven't been to setup this correctly yet.
=== Classic drivers
Those are the binaries and PPD files, which need to be installed for the device to work. This is older way of supporting devices, which will go away in the future.
=== Driverless printing (wireless/ethernet)
Most of modern devices (2010+) complies to AirPrint, Mopria or IPP Everywhere standard, which means they don't need a classic driver for being able to print. Those devices have IPP (Internet Printing Protocol) 2.0+ implemented within, are capable to 'advertise' themselves via mDNS and they support document formats like PDF, PCLm, JPEG, Apple Raster or PWG Raster.
There are several prerequitises which need to fulfill in OS to have an access to the driverless feature:
* avahi-daemon must run
* there needs to be a '.local' address resolver active - systemd-resolved or nss-mdns
* the device itself must have IPP port (631) and Bonjour/MDNS enabled
* IPP and MDNS need to be enabled in firewall
How does the driverless printing work under the roof (put it simply):
* CUPS sees the printer in mDNS messages via Avahi
* CUPS will find out the printer capabilities via IPP
* if there is a print job, CUPS will set up the filter chain to convert the incoming file into document format which printer understands (Apple Raster, PDF, PWG Raster, PCLm, JPEG)
In case it is needed, PPD file is generated by PPD generator in CUPS or by _driverless_ binary.
One of the features which use driverless printing is _CUPS temporary queues_.
See xref:cups-useful-tricks.adoc#_how_to_find_out_whether_my_printer_is_capable_of_driverless_printing[manual] how to check if your printer is capable of driverless printing.
=== Printing using a driver
This printing is similar to driverless printing in matter of setting up a filter chain, but:
* it can use limited mDNS and IPP functionality or it doesn't use them at all
* all information about device capabilities is taken from PPD (Postscript Printer Description) file
* can use a specialized filters and specialized communication with the device (depends on driver)
The downsides of this approach is to rely on 3rd party drivers, you need to always install a permanent queue for it and it will go away in the future.
=== Printing raw data
No filters are started during this printing, the data are sent as they are to the target. This approach is usually used for printing to label printers, or, in the past, for printing to remote CUPS queue. The same as classic drivers, this solution is deprecated and it will be removed in the future.
=== Printer applications
The binaries which provide support for older devices which aren't capable of complying to driverless standards. The core idea is they will be capable of accepting the old driver and then advertise itself as a device capable of driverless printing. Then the new CUPS will be able to see them and user will be able to print via them as if they were temporary queues. The currently available printer applications in Fedora are _ippeveprinter_ (a part of CUPS - see cups-printerapp package) and _lprint_ (provides support for devices which requires raw printing - mostly label printers). I'm planning to package https://www.msweet.org/pappl/[PAPPL], the library for creating printer applications, and https://github.com/OpenPrinting/ps-printer-app[ps-printer-app], a printer application for printers which support Postscript.
=== Driverless printing (USB)
Driverless printing has its variant for devices which are connected via USB - it is covered by 'IPP over USB' standard. For make it work, you need 'ipp-usb' package, which will register the device with Avahi on localhost - then USB device will look as a wireless/ethernet device. The discovery/printing looks the same as with a wireless/ethernet device with driverless support.
See xref:cups-useful-tricks.adoc#_how_to_find_out_whether_my_printer_is_capable_of_driverless_printing[manual] how to check for IPP-over-USB.
== Scanning
=== Classic scanning (via hplip and sane-backends)
The classic scanning works via backends, which are binaries for communication with device. There are several backends, usually created by reverse engineering communication between scanner and MS Windows driver. None of classic backends implements a protocol, which is compatible with most devices available.
=== Driverless scanning
The driverless scanning uses sane-escl (not built in Fedora) and sane-airscan backends for communicating with newer devices. Those newer devices usually support eSCL (based on AirScan protocol by Apple) or WSD (Web Services for Devices by Microsoft), which _sane-airscan_ is able to use.
Regarding USB scanning, it has the same requirement as printing. The device must support IPP over USB and 'ipp-usb' package must be installed to get driverless scanning via USB.

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[id='con_cups-useful-tricks']
= Useful tricks
== How to find out whether my printer is capable of driverless printing?
* look for AirPrint among device specification
* https://www.pwg.org/printers/[Officially certified printers for IPP Everywhere]
* check xref:_how_to_setup_cups_temporary_queues_with_network_printer[manual] for enabling CUPS temporary queues - if your printer is seen in the end in CUPS commands that way, your printer is capable of driverless printing
* [USB devices only] check for IPP over USB (xref:_how_to_find_out_if_my_usb_device_supports_ipp_over_usb[manual] here).
== How to find out my multifunction device or standalone scanner is capable of driverless scanning?
* check the device specification and look for eSCL/AirScan/WSD - if any of these are mentioned, the device is capable of driverless scanning
* most devices which advertise they can do AirPrint are capable of AirScan too
* [USB devices only] check for IPP over USB (xref:_how_to_find_out_if_my_usb_device_supports_ipp_over_usb[manual] here).
== How to find out if my USB device supports IPP over USB
Check whether your USB device has a following text in [command]`lsusb -v` output:
----
...
bInterfaceClass 7 Printer
bInterfaceSubClass 1 Printer
bInterfaceProtocol 4
iInterface 0
...
----
If the device has the _bInterfaceClass 7_, _bInterfaceSubClass 1_ and _bInterfaceProtocol 4_ in the sequence, it supports IPP over USB which is critical for USB device driverless printing and scanning.
== How to install a print queue
The answer is you don't have to install at all :) if your device is new enough, is in your local network or is an USB device, has IPP/AirPrint/mDNS enabled and your *avahi-daemon* is running, CUPS is able to create a temporary queue for you right away in the print dialog, print via it and remove it after successful printing. But there are still use cases when permanent installation is needed like sharing a print queue, different print queue defaults or printer being in different subnet, so I will cover a permanent instalation too.
=== How to setup CUPS temporary queues with network printer
If your printer is capable of AirPrint, IPP and MDNS is enabled in your printer and printer , then to get CUPS temporary queues working you need:
* have *avahi-daemon* running:
----
$ sudo systemctl start avahi-daemon
----
* have *cups.socket* enabled and running running:
----
$ sudo systemctl enable cups.socket
$ sudo systemctl start cups.socket
----
* enable IPP and MDNS in your firewall settings
After this the temporary queue will appear in the print dialog and you don't need to install a specific print queue unless you have a reason for it.
You can check if your printer is seen in mDNS messages by (*avahi-tools* must be installed):
----
$ avahi-browse -avrt
...
= enp0s25 IPv4 HP LaserJet M1536dnf MFP (42307C) _ipp._tcp local
hostname = [NPI42307C.local]
address = [192.168.1.10]
port = [631]
txt = ["UUID=434e4239-4243-4a42-5859-3c4a9242307c" "Scan=T" "Duplex=T" "Color=F" "note=" "adminurl=http://NPI42307C.local." "priority=10" "product=(HP LaserJet M1536dnf MFP)" "ty=HP LaserJet M1536dnf MFP" "URF=CP99,W8,OB10,PQ3-4-5,DM1,IS1-4,MT1-2-3-5,MT1-2-3-5,RS600" "rp=ipp/printer" "pdl=application/postscript,application/vnd.hp-PCL,application/vnd.hp-PCLXL,application/pdf,image/urf" "qtotal=1" "txtvers=1"]
...
----
and if CUPS or its backends see the printer by commands:
(lists all existing print queues - permanent or temporary)
----
$ lpstat -e
HP_LaserJet_M1536dnf_MFP_42307C_
----
or
(lists all devices, which CUPS sees in the local network or USB)
----
$ lpinfo -l -v
...
Device: uri = ipp://HP%20LaserJet%20M1536dnf%20MFP%20(42307C)._ipp._tcp.local/
class = network
info = HP LaserJet M1536dnf MFP (driverless)
make-and-model = HP LaserJet M1536dnf MFP
device-id = MFG:HP;MDL:LaserJet M1536dnf MFP;CMD:PDF,PS,PCL,AppleRaster,URF;
location =
...
----
=== How to setup CUPS temporary queues with USB printer
USB printers have only one additional prerequisite, installing *ipp-usb*, which will transform IPP over USB devices to network printer on localhost:
----
$ sudo dnf -y install ipp-usb
----
Then you can follow the steps in xref:_how_to_setup_cups_temporary_queues_with_network_printer[manual] for network printers.
=== How to install a permanent print queue
1) via CUPS web UI
* start cups.service
----
$ sudo systemctl start cups
----
* go to 'Administration' tab
* click on 'Add printer' and follow the dialogs
2) via CLI commands
* you will need a device uri - `<device_uri>`, f.e.:
----
$ lpinfo -l -v
...
Device: uri = ipp://HP%20LaserJet%20M1536dnf%20MFP%20(42307C)._ipp._tcp.local/
================================================================
----
and a driver name - `<driver>`, f.e.:
----
$ lpinfo -m
....
everywhere IPP Everywhere
==========
...
----
----
$ lpadmin -p <name> -v <device_uri> -m <driver> -E
----
where `<device_uri>` and `<driver>` are underscored strings from previous commands and `<name>` is a print queue name, which is chosen by you.
== How to install a scanner
Scanners in Linux don't have to be installed the same way as printers are if they are in the same network or connected via USB - you just need *sane-backends* to be installed and any scanning application will communicate with scanner/multifunction device via the backend which supports the scanner.
However, the older HP scanners and multifunction devices require an additional package - *hplip* - and its binary plugins downloaded via [command]`hp-plugin -i` if they aren't supported by sane-backends already.
=== How to make driverless scanning work
For LAN located and USB devices:
* have *avahi-daemon* enabled and running
----
$ sudo systemctl enable avahi-daemon
$ sudo systemctl start avahi-daemon
----
* enable MDNS in firewall
* [USB devices only] install *ipp-usb*
For network scanners in a different network:
* set the scanner device uri in [filename]`/etc/sane.d/airscan.conf` - see:
----
man sane-airscan
----
== How to setup mDNS with systemd-resolved
systemd-resolved is enabled and running by default since F33 and can be setup to work with Avahi on mDNS support which CUPS needs - Avahi does the advertising, registering and sharing devices, and resolved will handle '.local' address resolution. It will work with following steps:
* put [option]`MulticastDNS=resolve` into [filename]`/etc/systemd/resolved.conf`
----
$ sudo systemctl restart systemd-resolved
$ sudo nmcli connection modify <connection_name> connection.mdns yes connection.llmnr yes
$ sudo systemctl restart NetworkManager
----
== How to compress files
Example:
----
$ tar -czvf cups-information.tar.gz /etc/cups cups.logs troubleshoot.txt lpinfo.log
----
== Restarting cups service
You restart cups service with:
----
su -c 'systemctl restart cups.service'
----

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[id='proc_cups-user-stories']
= User stories
There are several common user stories when it comes to debugging printing issues. I'll mention some of them with steps how to get necessary information.
== I have HP printer and have a problem with HPLIP script
Please follow the steps in the following sections:
* xref:how-to-debug-printing-problems.adoc#_enable_cups_debug_logging[enable CUPS debug logging]
* xref:how-to-debug-printing-problems.adoc#_how_to_start_to_capture_incident_bound_journal_logging[start to capture journal logs]
* xref:how-to-debug-printing-problems.adoc#_hplip_scripts_debug_logging[run the script with enabled debugging]
* xref:how-to-debug-printing-problems.adoc#_how_to_get_incident_bound_journal_logging[get the journal logs]
* attach the files to the bugzilla ticket and xref:how-to-debug-printing-problems.adoc#_turning_off_debug_logging[turn off debug logging]
* provide printer model name and printer PPD file from `/etc/cups/ppd/`
== I have HP printer, installed it with HPLIP and have a problem with it
HPLIP installed print queue has a device uri starting with hp://.
Please follow the steps in the following sections:
* xref:how-to-debug-printing-problems.adoc#_enable_cups_debug_logging[enable CUPS debug logging]
* xref:how-to-debug-printing-problems.adoc#_how_to_start_to_capture_incident_bound_journal_logging[start to capture journal logs]
* trigger your issue
* xref:how-to-debug-printing-problems.adoc#_how_to_get_incident_bound_journal_logging[get the journal logs]
* attach the files to the bugzilla ticket and xref:how-to-debug-printing-problems.adoc#_turning_off_debug_logging[turn off debug logging]
* provide printer model name and printer PPD file from `/etc/cups/ppd/`
== My printer doesn't print correctly or at all, but I can see the printer in print dialog
Please follow the steps in the following sections:
* xref:how-to-debug-printing-problems.adoc#_enable_cups_debug_logging[enable CUPS debug logging]
* xref:how-to-debug-printing-problems.adoc#_prepare_cups_for_job_logging[prepare CUPS for job logging]
* xref:cups-useful-tricks.adoc#_restarting_cups_service[restart CUPS service]
* trigger your issue - print the specific document to the specific print queue you have problem with
* xref:how-to-debug-printing-problems.adoc#_get_a_job_log_for_a_specific_job_id[get the job log for the job you have just triggered]
* attach the created files to the ticket and xref:how-to-debug-printing-problems.adoc#_turning_off_debug_logging[turn off debug logging]
* attach your printer PPD file from `/etc/cups/ppd/` if available
* attach the file you wanted to print
* tell what application you printed from
* mention your xref:how-to-debug-printing-problems.adoc#_which_driver_am_i_using[printer model]
== CUPS generic issue
For generic issues - printer wasn't found, segfault - please follow the steps in the following sections (`avahi-daemon` must run):
* xref:how-to-debug-printing-problems.adoc#_enable_cups_debug_logging[enable CUPS debug logging]
* xref:how-to-debug-printing-problems.adoc#_how_to_start_to_capture_incident_bound_cupsd_logging[start to capture logs]
* trigger the issue - e.g. try to find printers via [command]`sudo lpinfo -l -v`, do some action in web ui - depends on your problem
* xref:how-to-debug-printing-problems.adoc#_how_to_get_incident_bound_cupsd_logging[get the logs]
* attach created files to the ticket and xref:how-to-debug-printing-problems.adoc#_turning_off_debug_logging[turn off debug logging]
* put the output of xref:how-to-debug-printing-problems.adoc#_what_make_and_model_is_my_printer[lpinfo] into a file and attach it
* put the output of xref:how-to-debug-printing-problems.adoc#_which_print_queues_are_available_for_me[both lpstat commands] into a file and attach it
== My printer doesn't print correctly - I use 'everywhere' model
Please follow the steps in the following sections:
* xref:how-to-debug-printing-problems.adoc#_cups_everywhere_model[get data from get-printer-attributes request]
* xref:how-to-debug-printing-problems.adoc#_my_printer_doesnt_print_correctly_or_at_all_but_i_can_see_the_printer_in_print_dialog[follow the steps with CUPS job log user story]
== I have a generic problem with cups-browsed
Please follow the steps in the following sections:
* xref:how-to-debug-printing-problems.adoc#_enable_cups_debug_logging[enable CUPS debug logging]
* xref:how-to-debug-printing-problems.adoc#_cups_browsed_logging[enable cups-browsed logging], but don't restart cups-browsed yet.
* xref:how-to-debug-printing-problems.adoc#_how_to_start_to_capture_incident_bound_cupsd_logging[start to capture cupsd logs]
* start cups-browsed via `systemctl` and start to capture its logs:
----
$ journalctl -u cups-browsed -f > cups_browsed_log
----
* trigger the issue or wait until cups-browsed triggers the issue itself
* cancel cups-browsed and xref:how-to-debug-printing-problems.adoc#_how_to_get_incident_bound_cupsd_logging[cupsd log] captures
* attach created files [filename]`cups_whole_log` and [filename]`cups_browsed_log` to the ticket and xref:how-to-debug-printing-problems.adoc#_turning_off_debug_logging[turn off debug logging]
== Printer found by cups-browsed doesn't print or print badly
The most difficult user story - we need to know how the print queue was created and how it behaves during printing. The print queue found by cups-browsed has a device uri starting with `implicitclass://`.
Please follow the steps:
* xref:how-to-debug-printing-problems.adoc#_cups_filters_driverless_driver[get printer info from get-printer-attributes and PPD file]
* xref:how-to-debug-printing-problems.adoc#_enable_cups_debug_logging[enable CUPS debug logging]
* xref:how-to-debug-printing-problems.adoc#_cups_browsed_logging[enable cups-browsed logging], but don't restart cups-browsed yet.
* xref:how-to-debug-printing-problems.adoc#_how_to_start_to_capture_incident_bound_cupsd_logging[start to capture cupsd logs]
* start cups-browsed via `systemctl` and start to capture its logs:
----
$ journalctl -u cups-browsed -f > cups_browsed_queue_creation
----
* give cups-browsed some time to process found devices (depends on how many devices you have in the local network or how many print queues are stored in the location you set with [option]`BrowsePoll` directive)
* cancel cups-browsed and xref:how-to-debug-printing-problems.adoc#_how_to_get_incident_bound_cupsd_logging[cupsd log] captures - save the files as `cups_queue_creation` and `cups_browsed_queue_creation`
Now we need to capture the logs during printing:
* xref:how-to-debug-printing-problems.adoc#_prepare_cups_for_job_logging[prepare CUPS for job logging]
* xref:cups-useful-tricks.adoc#_restarting_cups_service[restart CUPS service]
* start to capture cups_browsed logs again:
----
$ journalctl -u cups-browsed -f > cups_browsed_printing
----
* trigger your issue - print the specific document to the specific print queue you have problem with
* xref:how-to-debug-printing-problems.adoc#_get_a_job_log_for_a_specific_job_id[get the job log for the job you have just triggered] and cancel the capture of cups-browsed logging
* attach all gathered log files

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= Filing a bug report
:experimental:
include::{partialsdir}/attributes.adoc[]
== Deciding which component
Problems involving printing may relate to several components.
The configuration GUI (See above) is either https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=control-center[GNOME 3 System Settings application] or https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=system-config-printer[system-config-printer]. These packages also provide the printer applet, handle automatic queue creation, and disable/enable queues when USB printers are disconnected and reconnected.
Most GTK+ applications use the GTK+ print dialog. If the problem occurs when using GTK+ applications but not when printing from the command line or from another non-GTK+ application, the problem should probably be reported against https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=gtk2[gtk2]. If the problem occurs with only one GTK+ application, and other GTK+ applications print fine, the bug should be filed against that particular application.
If the problem only happens with PDF files, the bug may well be in https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=poppler[poppler] (the CUPS *pdftops* filter is a wrapper around one of the poppler utility programs).
Report bugs only seen using the *smb* backend against https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=samba[samba].
For bugs only seen when using the *hp* backend, or the hpijs or hpcups drivers, select https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=hplip[hplip] for the component.
For bugs for cups-browsed daemon and its printer discovery, please select https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=cups-filters[cups-filters]
Other possibilities, depending on the problem, include:
* https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=foomatic[foomatic] (the Foomatic CUPS filter and driver)
* https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=foomatic-db[foomatic-db] (the actual printer database used by Foomatic)
* https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=ghostscript[ghostscript] (which converts PostScript to other formats)
* https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=gutenprint[gutenprint] (a driver that supports very many printers)
For anything else, or if you are not sure, choose https://bugzilla.redhat.com/enter_bug.cgi?product=Fedora&component=cups[cups] or use your best guess.
== Other information to include
Be prepared to include some information about your system as well.
=== Before gathering of information
* Please change your OS locale to English. Manual xref:f{MAJOROSVER}@fedora:system-administrators-guide:basic-system-configuration/System_Locale_and_Keyboard_Configuration.adoc[[1\]].
* Please attach gathered information as archive (example is xref:cups-useful-tricks.adoc#_how_to_compress_files[here], you may need root permissions) to the bugzilla issue.
* Please do not forget to trigger your issue after debug enabling and restarting cups and before information gathering.
=== Information to gather
* the PPD file for the print queue (from the `/etc/cups/ppd` directory)
* the document you are attempting to print -- if the document is large, please try to see if the problem also occurs with a smaller document
* cupsd journal logs when debug level 2 is turned on. See the xref:how-to-debug-printing-problems.adoc#_enable_cups_debug_logging[how-to for turning debug2 on and for getting logs from systemd-journald].
* if the issue is connected to a print job, attach journal logs for this specific job too. How-to get logs xref:how-to-debug-printing-problems.adoc#_get_a_job_log_for_a_specific_job_id[here], example with JID. You can find out JID value by command:
----
$ lpstat -W all
----
Find your job there and JID is a number after '-'.
* If the issue is about f.e. 'printing from evince prints garbage, but printing from libreoffice works', then attach two separate files - first will contain logs when you print from evince, latter logs when you print from libreoffice.
* [filename]`troubleshoot.txt` from system-config-printer (BEWARE: it doesn't contain journal logs - don't forget to attach them too).
* xref:how-to-debug-printing-problems.adoc#_what_make_and_model_is_my_printer[make and model] of printer
* config files - [filename]`/etc/cups/client.conf` (if it contains any changes from default), [filename]`/etc/cups/cupsd.conf`
* if the issue is with cups-browsed and printer's discovery, attach [filename]`/etc/cups/cups-browsed.conf` and cups-browsed logs gained by xref:how-to-debug-printing-problems.adoc#_cups_browsed_logging[this how-to].
Some example documents can be found in the https://fedoraproject.org/wiki/Category:Printing_Test_Cases[Printing Test Cases category].
== Further reading
The https://fedoraproject.org/wiki/Printing[main printing page] has more information about how printing works in Fedora.

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= How to debug scanning issues
SANE library, communication libraries and backends can turn on and off debug logging via `SANE_DEBUG_*` environment variables.
The common environment variables:
* `SANE_DEBUG_DLL` - enables debugging SANE library
* `SANE_DEBUG_SANEI_USB` - enables debugging communication library for USB - add the environment variable if your device is connected via USB cable
* `SANE_DEBUG_SANEI_TCP` - enables debugging communication library for wireless/ethernet - add the environment variable if your device is connected by Wifi or Ethernet
Environment variables for enabling debugging a specific backends have a structure - `SANE_DEBUG_<backend_name>`, so the environment variable for f.e. *HPAIO* backend is `SANE_DEBUG_HPAIO*`.
You can find which SANE backend supports your device http://www.sane-project.org/sane-mfgs.html[here]. If your device is HP and it isn't supported by *airscan* backend or any other SANE backend, it can be supported by *hpaio* backend from *hplip* package, see the list of supported devices https://developers.hp.com/hp-linux-imaging-and-printing/supported_devices/index[here].
== Debugging scanner discovery
If you don't see your scanner in scanning application, then debugging of discovery process is in order. I prefer using [command]`scanimage` in the examples, but the similar steps can be applied for every scanning application like [command]`xsane`, [command]`scanadf`, [command]`simple-scan` etc.
You will need to use environment variables when you start a scanning application ([command]`scanimage` in this case). The environment variables used with [command]`scanimage` command depends on how your scanner is connected and which backend suppose to support it. So for getting debug logs for HP LaserJet device, *connected via Ethernet/Wifi and supported by HPAIO backend*, use command:
----
$ SANE_DEBUG_DLL=255 SANE_DEBUG_HPAIO=255 SANE_DEBUG_SANEI_TCP=255 scanimage -L &> discovery_output
----
or, f.e. if you have CanoScan 8600F, connected by USB and supported by genesys backend, use command:
----
$ SANE_DEBUG_DLL=255 SANE_DEBUG_GENESYS=255 SANE_DEBUG_SANEI_USB=255 scanimage -L &> discovery_output
----
Please attach the created [filename]`discovery_output` file as an attachment to the bugzilla ticket.
== Debugging scanning process
If the scanner is found, but an issue happens during scanning itself, we need to debug scanning process itself - which means debugging communication between backend and scanner when you start scanning a document.
The debugging scanning itself looks similar as discovery - setup the environment variables before running the command/scanning application and catch logs into a file. The possible command can be (f.e. if you have *network scanner supported by HPAIO backend*):
----
$ SANE_DEBUG_DLL=255 SANE_DEBUG_HPAIO=255 SANE_DEBUG_SANEI_TCP=255 xsane &> debug_log
----
or (once you find out device uri from [command]`scanimage -L` - see the xref:_getting_a_scanner_device_uri[next section]):
----
$ SANE_DEBUG_DLL=255 SANE_DEBUG_HPAIO=255 SANE_DEBUG_SANEI_TCP=255 scanimage -d <device_uri> > out.pnm 2> debug_log
----
, where you substitute `<device_uri>` for the actual device uri, f.e. 'hpaio:/net/laserjet_m1536dnf_mfp?ip=192.168.1.112'.
Please attach the created file - [filename]`debug_log` - as an attachment to the bugzilla ticket.
== Getting a scanner device uri
This point is basically a manual how to get a scanner uri for debugging scanning itself via [command]`scanimage`. You don't need to provide a scanner uri in GUI applications like [command]`xsane` or [command]`simple-scan`, because the application will do it for you or you can choose the scanner by a mouse click.
The [command]`scanimage -L` command returns an output where device uri of the device is shown, f.e.:
----
$ scanimage -L
device `v4l:/dev/video0' is a Noname Integrated Camera: Integrated C virtual device
device `hpaio:/net/laserjet_m1536dnf_mfp?ip=192.168.1.112&queue=false' is a Hewlett-Packard laserjet_m1536dnf_mfp all-in-one
----
F.e.the string 'hpaio:/net/laserjet_m1536dnf_mfp?ip=192.168.1.112&queue=false' is a device uri for for Hewlett-Packard laserjet_m1536dnf_mfp all-in-one scanner.
== Debugging HP scanner if it is supported by HPLIP
The hplip package doesn't have unified logging, so some logs come out of HPAIO backend to standard output and HP internal utilities logs come to journal. So we need to capture both to get the understanding of situation.
It can be done this way:
* start capturing journal logs at background:
----
$ journalctl -f > journal_logs &
----
* trigger an action (xref:_debugging_scanner_discovery[discovery] or xref:_debugging_scanning_process[scanning])
* kill the journalctl process, f.e. this way (if there is only one journactl process)
----
$ kill `pidof journalctl`
----
then attach the created file - [filename]`journal_logs` - as an attachment to the bugzilla ticket. Please do only one action per capture - that means if you are asked to attach log files for HP scanner discovery and scanning supported by hplip, you will attach as an attachment four files - [filename]`discovery_output`, [filename]`journal_logs` for discovery output, [filename]`debug_logs` and [filename]`journal_logs` for debug_logs.

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= Identifying your problem area
Printing issues can be fairly complex and active cooperation or lots of data can be requested from reporter by maintainer to helping maintainer to at least understand and (if it is not hardware specific issue) reproduce the issue, so please have a patience and try to narrow the problem as much you are able to for maintainers.
There can be:
* issues with seeing or connecting to the printer (it can be cups backend issues, avahi issues, libusb issues, cups-browsed issues),
* accessibility issues (correct/wrong setup in cupsd.conf or its bad interpretation by cupsd daemon, bad cooperation with NIS, SSSD...),
* printing with help of samba (issues with smb backend, which is part of samba) or with samba authenticated through Kerberos (samba_krb5_printing),
* issues with filters used during filtering the document into document format supported by printer, which influence how or if the document will be printed (issue with filters - pdftops, pdftopdf, pstops, bannertopdf etc. - or issues with binaries or libraries which filters uses - libgs, qpdf, poppler...),
* issues with Postscript Printer Description files, which are old way of defining printers capabilities like supported page sizes, borders etc...
Not mentioning possible limitations or issues in firmware or hardware of printer itself, so any kind of data or narrowing the issue is welcomed.
The best start is to attach files with logs described further down.
== CUPS logging
All CUPS logging is redirected to journal by default since Fedora 28 (there was a redirecting of error_log to journal by default before Fedora 28).
We need to define two different ways of capturing incident-bound CUPS whole logs - the one if the broken print queue isn't provided by HPLIP and the other if it is. They differs in the filter option of journald - if you use non-HPLIP queue for debugging, it is okay to gather the logs from cups systemd unit (by '-u cups'), because all error messages are correctly redirected to cups systemd unit logging and they are accessible in the output after unit filtering. HPLIP libraries are not implemented to do the same (upstream is unresponsive to accept a potencial fix into the project and the issue is not critical enough to drag a downstream patch forever), so their messages aren't marked for cups systemd unit and they're filtered out after calling journald with '-u cups'. For such queues journald log without filtering is required.
[NOTE]
===============================
Incident-bound journald log without filtering is required only for HPLIP print queues (their device uri starts with hp://) and it is unwanted for other queues, because it can be hard to read in larger cases. Please attach incident-bound journald log only when it is necessary.
===============================
=== Location of CUPS logging
CUPS logging is located in the system journal by default, but the logging into a file can be set in [filename]`/etc/cups/cups-files.conf` with directive [option]`ErrorLog`. If you want to change the default settings, then the name of the logging file is irrelevant, but it is recommended to put the file into path `/var/log/cups`, otherwise SELinux will block cupsd from accessing it.
Setting the logging to a file has following cons (without further operations):
* unable to get only logs connected to a job without chaining more commands
* unable to get logs for specified time frame without chaining more commands
For capturing a incident-bound logs `tail -f` can be used e.g.:
----
tail -f /var/log/cups/error_log
----
=== Enable CUPS debug logging
Enable full debugging information with:
----
$ sudo sed -i 's,LogLevel .*$,LogLevel debug2,' /etc/cups/cupsd.conf
$ sudo systemctl restart cups
----
=== CUPS job log
[IMPORTANT]
===============================
If the problem appears when you sent document to print or if you are trying to, capture logs for this job. If the job log is available, its attaching is *REQUIRED*.
===============================
==== Prepare CUPS for job logging
For being able to see specific job log, please turn on:
----
PreserveJobFiles Yes
----
in your [filename]`/etc/cups/cupsd.conf` file and restart cup service. Do not forget to remove the line after you are done with debugging. [command]`lpstat -W all` seems to be empty after printing if you do not enable the directive.
==== Get a job log for a specific job ID
To capture job log you need to know Job ID (JID) of the job - it is a number which together with print queue name specifies the job as request ID - for getting logs specific for the job.
Job ID can be seen in terminal if you send a document to print by [command]`lp` command:
----
$ lp -d <print_queue_name> <file1> ... <fileN>
request id is <print_queue_name>-<JID> (N file(s))
----
Or when you list jobs (see [command]`man lpstat`) - the latest job is at the end:
----
$ lpstat -W all
...
<print_queue_name>-<JID> <user> 1024 Wed 11 Jan 2017 05:52:19 PM CET
----
You can get the latest job logs automatically (if you have [command]`awk` installed and [command]`lpstat -W` all returns jobs) by:
----
$ journalctl -u cups JID=`lpstat -W all | awk '{print $1}' | awk -F '-' '{print $NF}' | tail -n 1` > cups_job_log
----
Or manually, if you found JID by yourself:
----
journalctl -u cups JID=<JID> > cups_job_log
----
=== Incident-bound cupsd log (broken print queue isn't HPLIP supported)
Sometimes we cannot bind the error with a specific print job, so the job log is uneffective. Incident-bound cupsd log is needed.
==== How to start to capture incident-bound cupsd logging
In new terminal/terminal tab, please issue:
----
journalctl -f -u cups > cups_whole_log
----
==== How to get incident-bound cupsd logging
After you trigger the error condition you are trying to diagnose e.g. printing something, try to find a printer via [command]`lpinfo` etc., you terminate capturing incident-bound cupsd log from xref:_how_to_start_to_capture_incident_bound_cupsd_logging[step above] by `<ctrl>+<c>`.
=== Incident-bound cupsd log (broken print queue is HPLIP supported)
Unfortunately, HPLIP libraries don't log into CUPS unit in journal, so if your print queue is installed with HPLIP driver (its device uri starts with `hp://`), we need incident-bound journal log.
==== How to start to capture incident-bound journal logging
In new terminal/terminal tab, please issue:
----
journalctl -f > journal_whole_log
----
==== How to get incident-bound journal logging
After you trigger the error condition you are trying to diagnose e.g. printing something, running HP script etc., you terminate capturing incident-bound journal log from xref:_how_to_start_to_capture_incident_bound_journal_logging[step above] by `<ctrl>+<c>`.
=== Turning off debug logging
Please attach [filename]`cups_job_log` for the problematic job, [filename]`cups_whole_log` or [filename]`journal_log` if you caught whole cupsd log during the problematic event to bug report as an attachment.
Then to turn off debugging information, do this:
----
$ sudo sed -i 's,LogLevel debug2,LogLevel warn,' /etc/cups/cupsd.conf
$ sudo systemctl restart cups
----
=== More commands for working with systemd-journald
View the log messages with:
----
journalctl -u cups -e
----
or:
----
journalctl -u cups --since=...
----
To filter out messages relating to a specific job ID, use:
----
journalctl -u cups JID=...
----
(tab completion will show you which job IDs have log messages)
== cups-browsed logging
cups-browsed daemon was introduced in Fedora around cups-1.5 version. It can browse Bonjour broadcasts, CUPS broadcasts (deprecated) and LDAP servers for printers and create or remove local queues pointing to those printers. It can creates broadcasts of local CUPS queues, but it is marked as deprecated.
For setting debug logging on you need to add:
----
DebugLogging stderr
----
to [filename]`/etc/cups/cups-browsed.conf`.
The logs will be available in system journal after cups-browsed restart.
== HPLIP scripts debug logging
Python scripts from HPLIP (e.g. [command]`hp-setup`, [command]`hp-clean`, [command]`hp-scan`) have debug logging redirected to the standard error file descriptor, so they are not logged in journal. For getting their debug logging, run the script with `-ldebug` parameter e.g.:
----
$ hp-setup -ldebug -i
----
and reproduce the issue. Then copy the messages from terminal into [filename]`hp_script_log`. Please attach the file to the bugzilla ticket too.
== What make and model is my printer?
Each different printer has a model-specific Device ID. You can find out with the [command]`lpinfo` command:
----
su -c "lpinfo -l -v"
----
This command runs each of the backends in discovery mode, to get them to report devices they can automatically detect. This will output a series of blocks of lines, each one like this:
----
Device: uri = usb://HP/DESKJET%20990C?serial=U123456789AB
class = direct
info = HP DESKJET 990C
make-and-model = HP DESKJET 990C
device-id = MFG:HEWLETT-PACKARD;MDL:DESKJET 990C;CMD:MLC,PCL,PML;CLS:PRI
NTER;DES:Hewlett-Packard DeskJet 990C;SN:U123456789AB;S:00808880800010032C100000
0C2000000;P:0800,FL,B0;J: ;
location =
----
The line which identifies this particular model type is the long one that starts "device-id =" (shown here wrapping over three lines).
Note that if your printer cannot be automatically detected, you may still be able to find out the Device ID by running the appropriate backend with the printer hostname as the argument. The *usb*, *parallel*, *snmp*, and *dnssd* backends all try to report the actual Device ID given by the printer.
----
$ /usr/lib/cups/backend/snmp 10.34.18.3
network socket://10.34.18.3 "HP Color LaserJet CP2025dn" "HP Color LaserJet CP2025dn"
"MFG:Hewlett-Packard;CMD:PJL,PML,PCLXL,POSTSCRIPT,PCL;MDL:HP Color LaserJet CP2025dn;
CLS:PRINTER;DES:Hewlett-Packard Color LaserJet CP2025dn;MEM:MEM=55MB;COMMENT:RES=600x8;" "HP Color LaserJet CP2025dn"
----
Device ID is in this case (see http://www.cups.org/documentation.php/doc-1.5/man-backend.html[backend(7)]) the last but one field.
== Which print queues are available for me?
The queues on your machine can be permanent ones or temporary. CUPS is capable to list all available print queues on the local network (permanent and temporary queues) by:
----
$ lpstat -e
----
For permanent queues you are able to get more info with:
----
$ lpstat -t
----
== Which driver am I using?
The PPD file for the printer queue can tell you which driver is in use. You can use this command to find out which driver is being used:
----
grep -H '^*NickName:' /etc/cups/ppd/*.ppd
----
You can also find this out using the [command]`system-config-printer` application. Double-click on the icon for the queue and look at the Make and Model field.
To see the available drivers, click on the _Change..._ button next to that field. You might find it useful to try another driver to see if that shows the same problem.
=== Driverless models
Most printers released since 2010 are capable of AirPrint or IPP Everywhere, which means they don't need to be installed to work - the device is found by Avahi and the print capabilities are communicated via IPP protocol - they are basically driverless devices. There are two solutions in Fedora which implement IPP everywhere:
- CUPS 'everywhere' model
- cups-filters 'driverless' driver
==== CUPS 'everywhere' model
It is CUPS implementation of IPP everywhere standard, available as a special printer model. The model is used when you use CUPS temporary queue for your device or if you install your device with as IPP Everywhere model in CUPS web ui or via lpadmin (using `-m everywhere`).
Because the created PPD file depends on IPP communication with printer, we need info which is gathered from the device. You can use [command]`ipptool` for that:
----
$ ipptool -tv <your_printer_device_uri> get-printer-attributes.test &> ipptool_log
----
Attach the created [filename]`ipptool_log` to the bugzilla ticket if needed.
==== cups-filters 'driverless' driver
Cups-filters special driver which is used for generating PPD according IPP Everywhere standard. The driver is used if you choose *driverless* model during printer installation.
We need get-printer-attributes request output too:
----
$ ipptool -tv <your_printer_device_uri> get-printer-attributes.test &> ipptool_log
----
and debug logs from the driver itself when it generates PPD for your device:
----
$ driverless -d cat <ipp_device_uri> 2> driverless_debug > created_ppd
----
Attach all created files to the bugzilla ticket if needed.
== Finding where the problem lies
When a print job is processed it is sent through a chain of _filters_ to convert the file into a format the printer can understand, and then finally sent to a _backend_, a program which can transport the data to the printer. By slightly changing how you print you can try a different printing path to see if that changes anything. If it works around the problem, you know which area the problem was in -- include that information in a bug report so that we can fix it.
=== Application
Try printing from a different application to see if the problem goes away or if it occurs regardless of how a file is printed. Try printing the document from the command line using the [command]`lp` command.
=== Document format
If you are having problems printing PDF files, try printing other types of file to see if the problem is with printing anything or if it is specific to printing PDF files. Try converting the file to a different format and printing that.
If the problem relates to printing text files, try removing/installing the paps package. This package provides an alternative text-to-PostScript filter to the one that comes with CUPS.
To inspect the document that was submitted to CUPS for printing, enable the [option]`PreserveJobFiles` option like this:
----
cupsctl PreserveJobFiles=yes
----
Submitted job documents will remain in `/var/spool/cups`. There are files with two types of names - [filename]`dXXXXX-YYY` and [filename]`cXXXXX`. [filename]`dXXXXX-YYY` is file which goes to CUPS system, unfiltered file - `XXXXX` is job ID, which is filled with zeros to be 5 characters long, and `YYY` is sequence number of file in the job. [filename]`cXXXXX` is file which contains printing options for a job specified by job ID in `XXXXX`. Please attach [filename]`dXXXXX-YYY` to the bug for a job when you experience the issue
==== Running filters by hand
More advanced users may like to try running the CUPS filters by hand and examining the data file at each step as it is converted between different formats. Here is an example of doing this for a gutenprint queue named pqueue with the CUPS test page which is its own special MIME type, `application/vnd.cups-banner`:
First you need to know the filter pipeline for `application/vnd.cups-banner` -> `printer/pqueue` (output MIME type). You can either xref:_enable_cups_debug_logging[enable debugging], print a test page, get xref:_cups_job_log[CUPS job log] and in cups_job_log you'll find something similar to:
----
envp[29]="FINAL_CONTENT_TYPE=printer/pqueue"
Started filter /usr/lib/cups/filter/bannertopdf (PID 1111)
Started filter /usr/lib/cups/filter/pdftopdf (PID 1112)
Started filter /usr/lib/cups/filter/gstoraster (PID 1113)
Started filter /usr/lib/cups/filter/rastertogutenprint.5.2 (PID 1114)
----
or run
----
/usr/lib/cups/filter/bannertopdf 1 me '' 1 '' </usr/share/cups/data/testprint >bannertopdf.pdf
cupsfilter -e -m printer/pqueue -p /etc/cups/ppd/pqueue.ppd bannertopdf.pdf > /dev/null
----
and you'll see:
----
INFO: pdftopdf (PID 1111) started.
INFO: gstoraster (PID 1112) started.
INFO: rastertogutenprint.5.2 (PID 1113) started.
----
[NOTE]
===============================
This filter pipeline is from cups-1.6. With cups < 1.6 you can see bannertops -> pstops -> pstoraster instead.
===============================
Now you can run filters by hand:
----
export PPD=/etc/cups/ppd/pqueue.ppd
/usr/lib/cups/filter/bannertopdf 1 me '' 1 '' </usr/share/cups/data/testprint >bannertopdf.pdf
/usr/lib/cups/filter/pdftopdf 1 me '' 1 '' <bannertopdf.pdf >pdftopdf.pdf
/usr/lib/cups/filter/pdftoraster 1 me '' 1 ''<pdftopdf.pdf >out.ras
/usr/lib/cups/filter/rastertogutenprint.5.2 1 me '' 1 ''<out.ras >out.prn
----
Here, [command]`evince` or [command]`okular` can be used to examine the output after the first two filters, [command]`rasterview` can be used to examine the output of the third filter, and the last filter's output must be inspected by hand or sent directly ([command]`lpr -oraw out.prn`) to the printer.
=== Driver
If you have access to a different make/model of printer it might be worth trying to see if the problem occurs on both of them or just one. This can give an indication about whether it is a problem with a particular driver, or if it is a more general problem.
Even if you only have access to the one printer there is often a choice of drivers to use for a given printer model, and trying each one in turn can be useful in narrowing down the problem. See xref:_which_driver_am_i_using[above] for how to do that.
==== Foomatic
For Foomatic drivers you can try enabling Foomatic debugging by editing the file [filename]`/etc/foomatic/filter.conf` and adding a line:
----
debug: 1
----
Next time you print a job to a queue using foomatic the debugging will be put in [filename]`/tmp/foomatic-rip.log`, and the input file as received by foomatic-rip will be in [filename]`/tmp/foomatic-rip.ps`.
=== Backend (job transport)
It may be possible for you to try a different backend. Using [command]`system-config-printer`, double-click on the printer queue icon and click the _Change..._ button next to the _Device URI_ field. You may see a _Connection_ expander arrow near the bottom right hand corner of the window -- click that to see which backends are available. For USB-connected HP printers, typically either of the *hp* and *usb* backends can be used.
For capturing USB communication:
* find out the bus number where USB device is connected, f.e.:
----
$ lsusb
Bus 002 Device 010: ID 03f0:012a HP, Inc HP LaserJet M1536dnf MFP
=
----
* start USB packet capture:
----
$ sudo tcpdump -i usbmonN -s0 -w usb.pcap
----
where N is the bus number.
For network printers you may have different protocols you can try.
* *socket* is for HP JetDirect (usually port 9100)
* *lpd* is for older style UNIX print shares
* *smb* is for CIFS shares from Windows systems
* *ipp* is for Internet Printing Protocol-enabled devices and also for other CUPS servers
-- You can capture the IPP traffic with [command]`tcpdump` like this (the interface name may differ from *p4p1*):
----
tcpdump -n -i p4p1 -U -s0 -w ipp.pcap port ipp
----
* *bjnp* is for Canon's proprietary bjnp network protocol (usually port 8611)
=== Configuration tool
If your problem relates to configuring print queues, try using one of the other methods of doing so. There are four available:
* The GNOME 3 System Settings application (*control-center*), _System Settings_ > _Printers_ from the GNOME Shell
* [command]`system-config-printer`, _System_ > _Administration_ > _Printing_ from the GNOME menu
* the CUPS web interface, http://localhost:631/
* the command line tools [command]`lpadmin`, [command]`lpoptions`, [command]`cupsctl`, [command]`cupsaccept`, [command]`cupsenable` etc.

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If you are experiencing a problem with printing, please take a look at the https://fedoraproject.org/wiki/Bugs/Common[common bugs] page before filing a bug. If the problem you are seeing is not listed there or none of the workarounds seem to help, please consider https://fedoraproject.org/wiki/How_to_debug_printing_problems#Filing_a_bug_report[filing a bug report] to help us make Fedora run better on your hardware.
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