I am also affected by this bug using version hplip 3.11.10 and Officejet_Pro_8500_A910. It is not possible to choose Two Sided in the printer dialog box. Under Installable Options in hp-toolbox the option Duplexer Installed is set to On but greyed out. Changing Double-Sided Printing to Short Edge or Long Edge doesn't help. Also, the Page Size "A4 AutoDuplex" is not available. Can't really see why you would need the cups error_log but I will attach it as you request.
** Attachment added: "error_log" https://bugs.launchpad.net/hplip/+bug/416513/+attachment/2638738/+files/error_log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/416513 Title: duplex printing no longer works for OfficeJetPro 8500 with HPLIP > 3.9.6b To manage notifications about this bug go to: https://bugs.launchpad.net/hplip/+bug/416513/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
