Visual Editor not showing up

Not sure where to start. Our website is powerdowndc.com. We update images on the site every month and otherwise don’t do much with the site in terms of the backend. The front end of the site is working fine, except that I really need to update the images and cannot.

Last month we got a weird string after updating each page that read “Warning: in_array() expects parameter 2 to be array, string given in /home/corwei5/powerdowndc.com/wp-content/plugins/download-media-library/download-media-library-admin.php on line 74” It repeated down a full page, but would update the edits.

Now I have tried to go in again, and the visual editor is not showing up at all, and (just to test it) when I hit “Preview” I get that same string.

All the plugins are updated, and our web designer tried turning them off one by one to see if any specific one was creating the problem. No change.

Any help would be greatly appreciated…