I read the thread under the topic titled "Cannot update firmware to Officejet Pro 8600 N911a". The question in that topic is reported by HP as SOLVED. Although it is true that question posed has been solved, HP has not corrected its erroneous listing of OJP8600_N911g-n_R1322C as the current firmware on the Software and Drivers Download web page for the HP Officejet Pro 8600 Plus e-All-in-One Printer - N911g Drivers.
I just wasted more than an hour of time trying to update my firmware just to finally learn by visiting the users forum that the R1322C is not the current firmware.
The problem is that the firmware update web page states that the effective date of the OLD firmare file CLP1CN1322CR 2014-07-18. So HP's website is still representing that old firmware as the most current version!
HP, how about correcting this erroneous listing so that another few thousand of your users are spared this totally wasteful experience.