An unfortunate code-signing mixup has broken printing to many HP printers for users of macOS 10.14 Mojave and 10.15 Catalina. HP unintentionally revoked the security certificate for some older printer drivers, causing macOS to warn that the drivers are malware and preventing printing. Some have assumed the fault lay with Apple, but an HP spokesperson told The Register that it was actually HP that revoked the credentials. HP is working with Apple to restore the certificates, but in the meantime, the company recommends uninstalling the HP driver and using the native AirPrint driver instead. One TidBITS reader also said he resolved the problem by removing his old drivers from System Preferences > Printers & Scanners and then downloading and reinstalling new drivers from HP’s support site.