Judging from the screenshot, it looks like that you have updated from NodeCanvas Lite version?
If so, please completely remove/delete the previous NodeCanvas Lite installation folder and re-import the new package from the asset store anew. You should preferably also always do that (clean re-install) whenever you update NodeCanvas by the way.
Please let me know if that was indeed the case and if the above works for you.
Thank you!
Gavalakis
