Error 500 is common on firmware versions prior to V6. 

Typically when the user tries to cancel a job while the printers is running or paused or if a user tries to delete a job from the machine memory.  

On earlier version of the mcor firmware (4-2.2 and earlier) you can  recover this by shutting down the printer and re-starting it.  (Note: Always shut down the machine using the Orange setup menu for safety)

On V6 firmware printers all of the operations described in the first paragraph can be carried out without errors.