Comment 24 for bug 416513

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.