Consumers who complained to HP were told the error was caused by using non-HP cartridges. A day later HP withdrew that statement and explained the issues were a side effect of a firmware update, [but] printers without any internet access started to reject non-HP cartridges. Therefore it's very unlikely that a firmware update caused the issues and the only other logical explanation is that HP programmed a date in its firmware on which non-HP cartridges would no longer be accepted.
"Printer worked fine for nine months," complains one of many angry users on HP's web site. "Then on 9/13 HP uploaded without my permission a firmware update that caused a message 'damaged cartridge' for all my cartridges and then it refused to print."