I am now having the issue of Error: "8506,421" appears on my Norton product. I have done the Reinst

Sorry, not  familiar with this yet.  I am having tje following issue. 

Error: "8506,421" appears on my Norton machine.

 

Can you help me?  I have done the uninstall/reinstall enough times, and still get this problem.  I see places that say problem solved, but can't seem to find that thread.  Can you please give me a hand?  Thanks, Steve