Getting HP DeskJet 3700 working with Xubuntu 20.04
Solution 1:
It's a nasty Apparmor problem!! I ran into this a couple of days ago with my EPSON-printer. Look at the syslog-audit-lines: apparmor denies access to /etc/passwd!
You can put ippbusxd in mode complain as explained here in the Ubuntu wwiki or disable Apparmor globally.