Printer trouble after power outage.

TDibs wrote:

Printer won't print after a recent power outage. Using a LaserJet Pro 400 M401dn

Computer gives this message - “hpPostProcessing.bundle” will damage your computer.

This is not a power outage problem/

HP's security certificate has expired. Search HP for a resolve here. 
Your Mac has encountered an expired security certificates.

https://h30434.www3.hp.com/t5/Printer-Setup-Software-Drivers/HP-Utility-fails-with-Code-Signature-Invalid-MacOS-10-15-7/td-p/7823883/highlight/true

Do not feel alone here, there is currently a HP issue…update your software:

Open >System Preferences>Software Update (Command R will reload and do a fresh check)

Update: HP Printer Software 5.1 should now be becoming available through Software Update to fix this issue.

(2220 UTC 23 October 2020)

or Apple direct download:

https://support.apple.com/kb/dl1888?locale=en_US

If you have continued issue:

The solution is to download this package which will update drivers AND THE CERTIFICATE:

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


download link above at the ftp address

If you still have an issue, and listed as AirPrint printer, delete the existing printer in

> System Preferences> Printers & Scanners, and add it again, select AirPrint.

Connect an AirPrint printer to a Wi-Fi network - Apple Support.

https://support.apple.com/en-us/HT201900

about AirPrint

https://support.apple.com/en-us/HT201311

you can also try reset print system if necessary:

If you can't print from your Mac or iOS device - Apple Support

https://support.apple.com/en-us/HT203343