"HPDeviceMonitoring.framework" will damage your computer.

The senior contributor here that posted the info Grant has provided has now modified his original post to recommend the new HP driver via System Preferences > Software Update:

It is Fixed, but requires you to do some more stuff:

From sources familiar with the matter, 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.

HP supplied a new driver on Friday to fix the issue:

ftp://ftp.hp.com/pub/softlib/software12/HP_Quick_Start/osx/Installations/Essentials/hp-printer-essentials-S-5_14_8_4.pkg

However, that "fix" is producing this error for some users:

"Matterhorn.framework" will damage your computer…

If you're seeing that, try this fix. Go to System Preferences, select Printers and Scanners. Select your printer from the list then delete (-) it. Then add (+) your printer back and select the generic driver to use.

Well, had I already tried this but update pane doesn't show this... so I went to HP.com and found it and downloaded it and the installer hangs... I also found the link posted in discussions and that led to the same result.

I cannot install the driver update - it just partially installs and then hangs there... now what? Thanks!