Everyone with the problem described here (HP printer with duplex unit does not print double-sided) please follow the instructions in the section "CUPS error_log" of https://wiki.ubuntu.com/DebuggingPrintingProblems. Thanks.
Everyone with the problem described here (HP printer with duplex unit does not print double-sided) please follow the instructions in the section "CUPS error_log" of https:/ /wiki.ubuntu. com/DebuggingPr intingProblems. Thanks.