Server Rendering error - ActionView::Template::Error (uninitialized constant ReactOnRails::Helper::ExecJS):

I’ve been using ReactOnRails for a few months now, and have been quite happy with it. I’m trying to test out server side rendering, but I keep getting this error in the log:

ActionView::Template::Error (uninitialized constant ReactOnRails::Helper::ExecJS):

I’ve seen older posts from about 2yrs ago referencing the same error. The solutions seemed to involve moving from therubyracer to mini_racer, which I already have. Any other suggestions?