Hello TiredTeacher,
Welcome to the HP Forums! I understand your Officejet 8500 is printing out blank pages. How is this printer connected? Wireless or USB?
I am going to recommend some troubleshooting steps to try and resolve your issue:
On you Mac computer, please reset the print system. I will provide a HP document here to help perform this step. Please try to print a document.
Next, try repairing your disk permissions. I will provide an Apple document here.
Please make sure you have performed every Apple update on your computer. I will provide an Apple document here.
If these steps don't resolve your issue, then please uninstall the printer's software. I will provide a HP document here.
Now, install the full feature software from the HP website here. Please choose your correct model number and operating system.
Once the installation is complete, try to print a document. If you are still receiving blank pages, then please contact Apple support for further assistance. Click here to find out: Apple Worldwide Contact.
Good Luck.