As a word of warning, if you've changed the output path in cups-pdf.conf, you need to make sure that the path in the /usr/lib/cups/backend/cups-pdf section of /etc/apparmor.d/usr.sbin.cupsd is updated too
e.g. change @{HOME}/PDF and @{HOME}/PDF/* to the right place.
Bruno M's solution worked well for me.
As a word of warning, if you've changed the output path in cups-pdf.conf, you need to make sure that the path in the /usr/lib/ cups/backend/ cups-pdf section of /etc/apparmor. d/usr.sbin. cupsd is updated too
e.g. change @{HOME}/PDF and @{HOME}/PDF/* to the right place.
Thanks,
Phil