Updated Many Mac users today found, to their surprise, they are unable to print to their HP Inc printers.
This is due to a code-signing snafu affecting macOS Catalina (version 10.15) and Mojave (10.14), specifically. HP's printer driver software is cryptographically signed with a certificate that macOS uses to determine whether the application is legit and can be trusted. However, that certificate was today revoked through an XProtect update, causing the software to be rejected by Macs.
XProtect is the mechanism Apple uses to inform Macs to no longer trust and run certain programs, and it does this by revoking their code-signing certificates. There is no central database of certs cancelled by XProtect, there's one for each OS version it seems, and Catalina and Mojave were selected in particular. Apple chose to revoke the HP driver cert, or perhaps was asked to do so by HP.
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In any case, HP's driver software no longer works on those two particular operating system flavors. Users are told when trying to print, for instance, that HP's application "will damage your computer," and are given the option to run it anyway or send it to the trash. Trying to continue just loops you back round to the error message, with no work done. Punters are also encouraged to report this "malware" to Apple.
Unofficial workarounds for now include using AirPrint to an HP printer, or uninstalling the HP software and using a generic PostScript driver.
A Reg reader who tipped us off about the blunder told us he was able to jerry rig some IPP connectivity to get an older device to print: "We had a handful of printers where macOS would print into the ether. Windows had no problem. I found some IPP trickery on macOS Catalina worked on an older HP4650."
We had a handful of printers where macOS would print into the ether. Windows had no problem
"Trying to open Printer Utility on MacOS 10.15.7 and I get a crash dump every time saying 'Code Signature Invalid' for the binary /Library/Printers/hp/Utilities/HP Utility.app/Contents/MacOS/HP Utility," said one netizen.
"Yes, my Deskjet F4140 abruptly stopped working with both my Mac mini desktop AND my partner's AirBook," complained another. "The AirBook keeps insisting it's malware (it's not), while my desktop says the certificate has expired. Suddenly, HP and Apple are NOT playing well together! I've redownloaded and reinstalled the printer software TWICE now but nothing has changed, just the same message about HP Utility now missing. Our jobs depend on this printer, HP."
Thomas Reed, director of Mac and mobile at Malwarebytes, tweeted to say his users were up in arms at the tech breakdown: "We're seeing a significant influx of support cases where users are seeing macOS identify what appear to be legit processes as malware."
Mac blogger Howard Oakley has some more background, here. "You’re seeing that [error] message because macOS is checking the signature on your HP printer software, and being told that its signing certificate has been revoked," he observed.
Amazon's Music desktop app is also, weirdly enough, no longer working, either, it's reported.
Spokespeople for HP and Amazon were not available for immediate comment. Apple declined to comment. ®
Updated to add
The Register understands from sources familiar with the matter that HP Inc asked Apple to revoke its printer driver code-signing certificates. It appears this request backfired as it left users unable to print. A HP Inc spokesperson told us on Friday night:
We unintentionally revoked credentials on some older versions of Mac drivers. This caused a temporary disruption for those customers and we are working with Apple to restore the drivers. In the meantime, we recommend users experiencing this problem to uninstall the HP driver and use the native AirPrint driver to print to their printer.