Updating the Mac iOS system seems like a great idea. Better graphics, apps and security. However, when you do so some printers just do not work like they did prior to the upgrade. What happened?
At the time El Capitan was created there were some printers that needed to catch up to the new software. After the upgrade is installed and the system completely updated the printer does not print. It is found in the printer’s dialogue window as well as when you uninstall it and reinstall. It is found on the network and when you use your iPad or iPhone to air print. Why is this an issue?
You will need to go to the manufacturer’s web site and upload the latest version of their software for your printer. In our case, the HP Envy 7640 needed to have the latest software installed. Once that was done, the printer acted normally. All is well again.