If you have an .rfu file, you can send it via Terminal using the command: nc -w 100 [Printer_IP] 9100 < firmware_file.rfu .

If you are looking to downgrade the firmware on your HP OfficeJet Pro 8620, you are likely facing one of two common scenarios: your printer is refusing to work with third-party ink cartridges, or a recent update has caused connectivity or scanning issues.

You cannot reliably downgrade firmware over Wi-Fi. You must have a USB cable (Type A to Type B) connecting your computer to the printer.

Firmware updates are marketed as security or performance enhancements, but they frequently contain "Dynamic Security" code that checks for a special chip on ink cartridges. If the chip is third-party, the printer locks out.

To successfully downgrade, you must first prepare the printer to accept an older file and then manually push that file to the machine.

If your 8620 suddenly reports "Cartridge Error," "Missing or Damaged Cartridge," or "HP Chip Error" after an update, you are likely facing this issue. is the primary way to restore functionality and regain the freedom to use cheaper cartridges.

Once you have successfully downgraded your printer, it is crucial to stop it from updating again.