Drivers are software that some hardware or application uses to communicate with an operating system. In other words, a functional and authorized driver is essential to ensure that items such as printers, scanners, game controllers and other peripherals work with a computer’s operating system. Sometimes, drivers stop working because of bugs, which leaves users with hardware that they cannot use until they are fixed. The case with Macs and HP printers, however, is quite unusual because the root cause may actually be some communication failure and carelessness.
Because of how deeply they can exploit the functions of the operating system, drivers are often required to undergo some form of security check or certification in order for them to work. In macOS, this is done using cryptographically signed certificates that tell macOS and its XProtect framework that this or that driver and this or that driver version is safe to run. With the latest XProtect update, however, HP printer drivers are no longer certified.
This announced change caused users a big surprise and concern. In addition to not being able to print, they were also warned that the HP printer driver is malware that can be used to damage your Macs. Of course, some may have feared real malware or a compromise on the HP side. The truth, as they say, is stranger than fiction.
In statements to The Register, HP confirmed that it asked Apple to revoke certificates for some older versions of its drivers. Neither HP nor Apple warned users, and the action, unsurprisingly, caused the printers to suddenly stop working and receive a sinister warning. The drivers, however, can be completely safe anyway.
However, it is not the end of HP printing on macOS, as it appears to affect only macOS 10.15 Catalina and macOS 10.14 Mojave. HP also says it is working with Apple to restore these drivers, but users who really need to print immediately can use AirPrint in the meantime.