Cartridge problem when replacing ink in a HP OfficejetPro 8600
Product: HP Officejet Pro 8600 Printer
I have a HP Officejet Pro 8600 Printer that was low in ink. I replaced all ink cartridges with genuine HP cartridges 950XL and 951XL and now I have a message on the printer stating "one or more cartridges appear to be damaged" It also shows the letter K which refers to the black cartridge. I got another new genuine HP 951XL black ink cartridge and replaced it again and still show this message. I had no trouble with printing before replacing cartridges and there is no way I could have damaged the printer while replacing the ink cartridges as it's a simple push in and they pop out.
Has anyone else had this issue before? How can I fix it. I have spent a fortune on genuine HP ink cartridges and now nothing is working.