Large numbers of HP printer owners found their printers stopped recognising unofficial printer ink cartridges on 13 September.
Dutch printer ink vendor 123inkt
said it had received more than 1,000 complaints in one day.
HP said that during its last firmware update, settings had been changed so HP printers would communicate with only HP-chipped cartridges.
It also said some devices already had the functionality built-in.
123inkt said it did not believe that a firmware update had been issued since March 2016, suggesting the change had been pre-programmed to roll out this month.
HP said such updates were rolled out "periodically" but did not comment on the timing of the last instalment.
"The purpose of this update is to protect HP's innovations and intellectual property," it said in a statement.
It has angered some of its customers as HP branded cartridges are notably more expensive than unofficial brands.
'Cartridge problem'
Reported error messages include "cartridge problem", "one or more cartridges are missing or damaged" or "older generation cartridge".
One contributor to HP's support forum said the firmware had been updated "without my permission" and an error message now said the ink cartridge was damaged.
"I use it daily for work and now am in trouble," he wrote.
"Others must have the same problem. Is there a way to stop HP from doing this to people who have bought their equipment?"
The HP OfficeJet, OfficeJet Pro and OfficeJet Pro X printers are affected.
Chipped cartridges filled with alternative ink would still work, HP told the BBC.
It said: "These printers will continue to work with refilled or remanufactured cartridges with an original HP security chip. Other cartridges may not function.
"In many cases, this functionality was installed in the HP printer and in some cases it has been implemented as part of an update to the printer's firmware," it added.
'(Un)intended result'
123inkt said it had been able to develop new chips for its own label of cartridges that were compatible, and these were currently in production, but that the problem itself was not unusual.
"Printer manufacturers regularly execute firmware-updates, claiming that they improve the operation of the printer or solve security issues," it said.
"The (un)intended result usually is that the operation of lower price private label cartridges is disturbed and error messages are triggered."
Problems? See this thread at archive.org.)