Understanding and Resolving “Filter Failed” Errors in CUPS Printing: A Practical Guide

Encountering a “Filter failed” error while using your printer in a Linux environment, specifically within the CUPS (Common UNIX Printing System) framework, can be a frustrating experience. This guide aims to shed light on this issue and provide a practical solution, using a Samsung M2020 Series printer on Debian 12 as a concrete example. Cups Printing is a cornerstone of printing management in many Unix-like operating systems, and understanding how to troubleshoot common errors is essential for a smooth printing workflow.

When setting up a printer with CUPS, drivers are crucial for translating print jobs into a language the printer understands. In the case of Samsung printers, manufacturers often provide specific drivers for Linux systems. Let’s consider a scenario where a Samsung M2020 Series laser printer (specifically the Xpress SL-M2022W model) is installed on Debian 12 bookworm (x86_64 amd64) using the official “Samsung Print Driver for Linux”. The printer is configured through the CUPS web interface (typically accessed via http://localhost:631/admin) and set up using the PPD (PostScript Printer Description) file for the “Samsung M2020 Series”.

Despite seemingly correct installation and setup, attempts to print might fail, resulting in a “Filter failed” error message displayed in the CUPS job queue (accessible at http://localhost:631/jobs?which_jobs=all). Digging deeper into the CUPS error logs, located at /var/log/cups/error_log, often reveals more specific clues. In this particular Samsung printer case, the error log might contain entries similar to:

... D [18/Jan/2024:14:14:59 +0100] [Job 3] Started backend /usr/lib/cups/backend/dnssd (PID 24300) D [18/Jan/2024:14:14:59 +0100] [Job 3] Samsung_M2020_Series: error while loading shared libraries: libcupsimage.so.2: cannot open shared object file: No such file or directory D [18/Jan/2024:14:14:59 +0100] [Job 3] PID 24299 (/usr/lib/cups/filter/rastertospl) stopped with status 127 (File too large) ...

This error message points towards a missing dependency. The Samsung printer driver for Linux, like many CUPS printer drivers, utilizes filters to process print data. In this case, the PPD file Samsung_M2020_Series.ppd specifies a CUPS filter named rastertospl. This filter, provided by Samsung and installed at /opt/smfp-common/printer/bin/rastertospl, is responsible for converting raster data into a printer-specific format (SPL).

The error message “error while loading shared libraries: libcupsimage.so.2: cannot open shared object file: No such file or directory” indicates that the rastertospl filter depends on a shared library called libcupsimage.so.2 which is not found by the system. To confirm this dependency, the ldd command-line utility can be used to list the dynamic dependencies of the rastertospl executable:

ldd /opt/smfp-common/printer/bin/rastertospl

The output will list all shared libraries that rastertospl requires, and among them, you should find libcupsimage.so.2. If this library is indeed missing from the system’s library paths, it explains why the filter fails to load, leading to the “Filter failed” error in CUPS printing.

To resolve this, we need to identify the package that provides the missing libcupsimage.so.2 library. On Debian-based systems like Debian 12, the apt-file search command (which may require installation via sudo apt install apt-file and updating its database with sudo apt-file update) is invaluable for this purpose:

apt-file search libcupsimage.so.2

The output will reveal that the libcupsimage.so.2 library is part of the libcupsimage2 package on Debian. Therefore, installing this package using the command:

sudo apt install libcupsimage2

will provide the missing library. After installing libcupsimage2, restarting the CUPS service might be necessary, or simply attempting to print again should now succeed. The “Filter failed” error should be resolved, and CUPS printing with the Samsung M2020 printer on Debian 12 should function correctly.

It’s worth noting that on other Linux distributions, such as Arch Linux, the libcupsimage.so.2 library might be provided by a different package, in Arch’s case, it is included within the libcups package itself.

In conclusion, the “Filter failed” error in CUPS printing, especially when using manufacturer-provided drivers, can often be attributed to missing library dependencies for printer filters. By examining CUPS error logs and using tools like ldd and apt-file (or their equivalents on other distributions), you can diagnose and resolve these issues by installing the necessary dependency packages. This example with a Samsung printer and Debian highlights a common troubleshooting process applicable to various CUPS printing scenarios and helps ensure reliable cups printing functionality.