Here is an excerpt from the /var/log/cups/error_log:

E [21/Jun/2019:07:05:30 -0400] [Job 3087] Job stopped due to filter errors; please consult the error_log file for details.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] The following messages were recorded from 07:05:30 AM to 07:05:30 AM
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Adding start banner page "none".
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Queued on "DELIVER" by "apache".
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Auto-typing file...
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Request file type is application/pdf.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] File of type application/pdf queued by "apache".
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Adding end banner page "none".
D [21/Jun/2019:07:05:30 -0400] [Job 3087] time-at-processing=1561115130
D [21/Jun/2019:07:05:30 -0400] [Job 3087] 2 filters for job:
D [21/Jun/2019:07:05:30 -0400] [Job 3087] pdftopdf (application/pdf to application/vnd.cups-pdf, cost 66)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] foomatic-rip (application/vnd.cups-pdf to printer/DELIVER, cost 0)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] job-sheets=none,none
D [21/Jun/2019:07:05:30 -0400] [Job 3087] argv[0]="DELIVER"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] argv[1]="3087"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] argv[2]="apache"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] argv[3]="1561115130.pdf"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] argv[4]="1"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] argv[5]="finishings=3 number-up=1 job-uuid=urn:uuid:9ac877bb-51a8-3226-6a37-fec131d144d9 job-originating-host-name=localhost time-at-creation=1561115130 time-at-processing=1561115130"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] argv[6]="/var/spool/cups/d03087-001"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[0]="CUPS_CACHEDIR=/var/cache/cups"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[1]="CUPS_DATADIR=/usr/share/cups"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[2]="CUPS_DOCROOT=/usr/share/cups/www"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[3]="CUPS_FONTPATH=/usr/share/cups/fonts"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[4]="CUPS_REQUESTROOT=/var/spool/cups"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[5]="CUPS_SERVERBIN=/usr/lib/cups"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[6]="CUPS_SERVERROOT=/etc/cups"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[7]="CUPS_STATEDIR=/var/run/cups"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[8]="HOME=/var/spool/cups/tmp"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[9]="PATH=/usr/lib/cups/filter:/usr/lib64/cups/filter:/usr/bin:/usr/sbin:/bin:/usr/bin"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[10]="[email protected]"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[11]="SOFTWARE=CUPS/1.6.3"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[12]="TMPDIR=/var/spool/cups/tmp"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[13]="USER=root"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[14]="CUPS_MAX_MESSAGE=2047"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[15]="CUPS_SERVER=/var/run/cups/cups.sock"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[16]="CUPS_ENCRYPTION=IfRequested"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[17]="IPP_PORT=631"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[18]="CHARSET=utf-8"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[19]="LANG=en.UTF-8"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[20]="PPD=/etc/cups/ppd/DELIVER.ppd"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[21]="RIP_MAX_CACHE=128m"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[22]="CONTENT_TYPE=application/pdf"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[23]="DEVICE_URI=socket://192.168.1.156"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[24]="PRINTER_INFO=DELIVER"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[25]="PRINTER_LOCATION=DELIVER"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[26]="PRINTER=DELIVER"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[27]="PRINTER_STATE_REASONS=none"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[28]="CUPS_FILETYPE=document"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[29]="FINAL_CONTENT_TYPE=application/vnd.cups-pdf"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] envp[30]="AUTH_I****"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Started filter /usr/lib/cups/filter/pdftopdf (PID 19077)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Started filter /usr/lib/cups/filter/foomatic-rip (PID 19078)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Started backend /usr/lib/cups/backend/socket (PID 19079)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Getting input from file
D [21/Jun/2019:07:05:30 -0400] [Job 3087] foomatic-rip version 4.0.17.256 running...
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Parsing PPD file ...
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Added option ColorSpace
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Added option PageSize
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Added option ImageableArea
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Added option PaperDimension
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Added option InputSlot
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Added option Resolution
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Added option Font
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Parameter Summary
D [21/Jun/2019:07:05:30 -0400] [Job 3087] -----------------
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Spooler: cups
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Printer: DELIVER
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Shell: /bin/bash
D [21/Jun/2019:07:05:30 -0400] [Job 3087] PPD file: /etc/cups/ppd/DELIVER.ppd
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ATTR file:
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Printer model: HP LaserJet Foomatic/laserjet (recommended)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Job title: 1561115130.pdf
D [21/Jun/2019:07:05:30 -0400] [Job 3087] File(s) to be printed:
D [21/Jun/2019:07:05:30 -0400] [Job 3087] <STDIN>
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Ghostscript extra search path ('GS_LIB'): /usr/share/cups/fonts
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Printing system options:
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Pondering option 'finishings=3'
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Unknown option finishings=3.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Pondering option 'number-up=1'
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Unknown option number-up=1.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Pondering option 'job-uuid=urn:uuid:9ac877bb-51a8-3226-6a37-fec131d144d9'
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Unknown option job-uuid=urn:uuid:9ac877bb-51a8-3226-6a37-fec131d144d9.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Pondering option 'job-originating-host-name=localhost'
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Unknown option job-originating-host-name=localhost.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Pondering option 'time-at-creation=1561115130'
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Unknown option time-at-creation=1561115130.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Pondering option 'time-at-processing=1561115130'
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Unknown option time-at-processing=1561115130.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Options from the PPD file:
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ================================================
D [21/Jun/2019:07:05:30 -0400] [Job 3087] File: <STDIN>
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ================================================
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: +connecting-to-device
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Looking up "192.168.1.156"...
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Filetype: PDF
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Storing temporary files in /var/spool/cups/tmp
D [21/Jun/2019:07:05:30 -0400] [Job 3087] PID 19077 (/usr/lib/cups/filter/pdftopdf) exited with no errors.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Process is dying with "Unable to determine number of pages, page count: -1
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ", exit stat 3
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Cleaning up...
D [21/Jun/2019:07:05:30 -0400] [Job 3087] PID 19078 (/usr/lib/cups/filter/foomatic-rip) stopped with status 3.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] Hint: Try setting the LogLevel to "debug" to find out more.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] hrDeviceDesc="HP LaserJet M402n"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] prtMarkerColorantValue.1.1 = "black"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ATTR: marker-colors=#000000
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ATTR: marker-names='"Black Cartridge HP CF226A"'
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ATTR: marker-types=toner
D [21/Jun/2019:07:05:30 -0400] [Job 3087] ATTR: marker-levels=100
D [21/Jun/2019:07:05:30 -0400] [Job 3087] new_supply_state=0, change_state=ffff
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -developer-low-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -developer-empty-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -marker-supply-low-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -marker-supply-empty-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -opc-near-eol-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -opc-life-over-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -toner-low-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -toner-empty-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -waste-receptacle-almost-full-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -waste-receptacle-full-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -cleaner-life-almost-over-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -cleaner-life-over-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] new_state=0, change_state=ffff
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -media-empty-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -door-open-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -media-jam-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -input-tray-missing-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -output-tray-missing-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -marker-supply-missing-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -output-area-almost-full-report
D [21/Jun/2019:07:05:30 -0400] [Job 3087] STATE: -output-area-full-warning
D [21/Jun/2019:07:05:30 -0400] [Job 3087] backendWaitLoop(snmp_fd=6, addr=0x55a74886ab38, side_cb=0x55a748630340)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] PID 19079 (/usr/lib/cups/backend/socket) exited with no errors.
D [21/Jun/2019:07:05:30 -0400] [Job 3087] End of messages
D [21/Jun/2019:07:05:30 -0400] [Job 3087] printer-state=3(idle)
D [21/Jun/2019:07:05:30 -0400] [Job 3087] printer-state-message="Filter failed"
D [21/Jun/2019:07:05:30 -0400] [Job 3087] printer-state-reasons=none
E [21/Jun/2019:07:10:32 -0400] [Job 3087] Stopping unresponsive job.