CoreDragCreate error - drag&drop and copy-paste stop working
I don't know what is causing the issue, but the pboard process is responsible for copy and paste.  Restarting it might provide a fix (temporarily), and can be less disruptive than logging out.  From this answer:


  Check if the pboard daemon is running:
  
  launchctl list | grep com.apple.pboard
  
  If the pboard daemon is running, then stop and start it. If it's not running, start it:
  
  launchctl stop com.apple.pboard
  
  launchctl start com.apple.pboard
  
  Then, you may need to restart the application(s) where cut-and-paste is not working.