Following a firmware upgrade on selected printers utilizing the following cartridges, 934 / 935 / 950 / 951 / 970 / 971 some cartridges suddenly stopped working.
HP indicated in a statement that the reason for the upgrade was to protect the security chip. However, this upgrade was done automatically and without customer consent. Consequently, millions of customers across the world were all the sudden unable to print. So, under pressure from all the different consumer groups, HP announced that they would release a firmware to reverse the unsolicited upgrade. Those upgrades are now available on the HP Support website under the client’s specific printer model.
A procedure is available with a link to the different printer models. Simply follow the instructions for the upgrade/downgrade.
Visit this link to know the procedure for your printer model :
Currently may effect the following printers:
OfficeJet Pro 6230 series
OfficeJet 6810 series
OfficeJet 6820 series
OfficeJet Pro 6830 series
OfficeJet Pro 8610, 8615, 8616 series
OfficeJet Pro 8620, 8625 series
OfficeJet Pro 8630 series
OfficeJet Pro 8640 series
OfficeJet Pro 8660 series
OfficeJet Pro X451dn
OfficeJet Pro X451dw
OfficeJet Pro X476dn
OfficeJet Pro X476dw
OfficeJet Pro X551dw
OfficeJet Pro X576dw