CUPS says job completed but the PDF doesnt print, wile printing via lpr works

[Vlado]

Driver installed from manufacturer's website, test page prints OK on USB printer Brother DCP-1510.

When I send the PDF document for printing, the printer displays "Receiving data" but then nothing prints. CUPS says "job completed" and I cant discern any useful errors in /var/log/cups/error_log

Printing the same document via lpr <doc name> worked -- the document printed fine.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: cups 2.2.7-1ubuntu2.4
ProcVersionSignature: Ubuntu 4.18.0-18.19~18.04.1-generic 4.18.20
Uname: Linux 4.18.0-18-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
CurrentDesktop: XFCE
Date: Wed May 15 12:08:27 2019
InstallationDate: Installed on 2019-04-12 (32 days ago)
InstallationMedia: Xubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
Lpstat: device for Brother-DCP-1510-series: usb://Brother/DCP-1510%20series?serial=E72065A8N348435
MachineType: Hewlett-Packard HP Z420 Workstation
Papersize: letter
PpdFiles: Error: command ['fgrep', '-H', '*NickName', '/etc/cups/ppd/Brother-DCP-1510-series.ppd'] failed with exit code 2: grep: /etc/cups/ppd/Brother-DCP-1510-series.ppd: Permission denied
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.18.0-18-generic root=UUID=b3062c40-ce3c-4a67-9e83-4bca7967e954 ro quiet splash vt.handoff=1
SourcePackage: cups
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/07/2013
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: J61 v02.55
dmi.board.asset.tag: JPWH505625
dmi.board.name: 1589
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 0.00
dmi.chassis.asset.tag: JPWH505625
dmi.chassis.type: 6
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvrJ61v02.55:bd02/07/2013:svnHewlett-Packard:pnHPZ420Workstation:pvr:rvnHewlett-Packard:rn1589:rvr0.00:cvnHewlett-Packard:ct6:cvr:
dmi.product.family: 103C_53335X G=D
dmi.product.name: HP Z420 Workstation
dmi.product.sku: LJ449AV
dmi.sys.vendor: Hewlett-Packard

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.