HP printer not working after Catalina upgrade - Problem fixed!
Crude solution:
My HP C4400 Photosmart printer did not work after upgrading the Mac to Catalina.
I read the thread here on this problem and downloaded the recommended package from HP.
The printer still did not work. The Mac still claimed that the printer driver was "malware".
So I chose "Show in Finder" and simply removed the files that were called "malware": HPDM (the whole folder) and a file called pdftopdf.
And ... Presto! The printer worked again.
Hope this can help others!
It is a scandal that Mac and HP don't assume better responsibility for this issue. Many thousands of printers grinded to a halt and discarded for a small software issue.
MacBook Air 13″, macOS 10.15