Re-add your printer from the print queue to resolve the HP printer offline Mac issue. Hit 
the icon of Spotlight and open Printers & Scanners. Tap the name of your HP printer and 
choose the Remove Printer option. Now, tap Remove Printer when the prompt appears. 
After that, tap Add Printer, Scanner, or Fax. Choose your HP printer followed by 
tapping the Add option. You can also restart the printer to fix the offline error.