On Monday,  2 Oct 2017 at 10:24, Peter Davis wrote:

[...]

> I added (gnuplot . t) to my org-babel-load-languages, and now I'm back
> to
>
> Wrong type argument: arrayp, nil

Very strange.  Try M-x toggle-debug-on-error RET and then post a
backtrace?
Also maybe post your complete example.
What versions of gnuplot and org do you have installed?

-- 
: Eric S Fraga via Emacs 27.0.50, Org release_9.1.1-78-gfbf47c