Qt - 5.10.1
KDE Apps - 18.03.08
Вот что имеем
$ okular --print ${name}.pdf
/usr/bin/lpr: No such file or directory
$ gwenview
QPainter::begin(): Returned false
QPainter::viewport: Painter not active
alignment= 132
QPainter::setViewport: Painter not active
QPainter::setWindow: Painter not active
$ kolourpaint
kf5.kio.core: KSambaShare: Could not find smb.conf!
QPainter::begin(): Returned false
QPainter::end: Painter not active, aborted
$ qpfview
Could not print ${name}.pdf
$ equery b /usr/bin/lpr
* Searching for /usr/bin/lpr ...
net-print/cups-2.2.7 (/usr/bin/lpr)
$ whereis lpr
lpr: /usr/bin/lpr /usr/share/man/man1/lpr.1.bz2
Принтер подключён по сети.
На другом компе, к которому подключён принтер, установлены те же версии KDE/Qt, там всё работает.