Edit the /etc/cups/cupsd.conf file, find the section "loglevel" change "info" to "debug" save and exit then restart cups

# /etc/init.d/cups restart

or for Ubuntu

$ sudo /etc/init.d/cupsys restart

then enter this command to view the log

tail -f /var/log/cups/error_log

With the CUPS LogLevel set to debug, the CUPS error_log will show all programs that are executed during the print job. Generally there are two data paths taken during a print job; 1) HPIJS driver path 2) Postscript driver path. Both data paths will use the "hp" backend.

For the HPIJS path, look for errors near the ghostscript command (gs) command. The gs command will invoke the HPIJS driver.

For the Postscript path, there will be no gs command. Postscript will be passed directly to the "hp" backend and then to the printer.