Problem
Error Message
[insert file name below]… "will damage your computer. This file was downloaded on an unknown date."
Issue
Apple Mac running OS X Catalina computer printing to an HP printer, starts showing warning dialogs referring to HP printing related files "will damage your computer". The warning may refer to one of the following files.
hpPostScriptPDE.plugin
hpPostProcessing.bundle
Answer
To resolve the issue, download (and install) the HP Printer Drivers v5.1 for OS X. Once installed, restart your computer.