Hp Officejet Pro 8620 Firmware Downgrade Hot Exclusive -

HP removed old firmware from their site. Try:

This method involves sending an older firmware file (often with a extension) directly to the printer using a computer. Requirements hp officejet pro 8620 firmware downgrade hot

) can often resolve these "Non-HP Chip Detected" or "Older Generation Cartridge" errors. Step-by-Step Downgrade Process HP removed old firmware from their site