from $ cat /etc/udev/rules.d/55-hpmud.rules
...
2. It seems SFSFS has been replaced or depreciated by ATTR/ATTRS, but I continue to use SFSFS in order to be compatible with
# older distros. SFSFS was defined in "Writing udev rules" Ver 0.72, Daniel Drake. 2/11/2009, D Suffield
...
# photosmart_d2300_series
SYSFS{idVendor}=="03f0", SYSFS{idProduct}=="c302", OWNER="tc", GROUP="staff", MODE="660"
..
This would explain the error messages you see - odd that if I load the hplip extension and then "udevadm trigger" I don't see anything in dmesg...