Hi Mike and thank you for the response!
The current version I already have installed, and have had installed for a few years now that has worked until I upgraded to my current version of Joomla, is 2.5.4. If I upgrade EFL, it breaks my Joomla site to the point where I have to recover it from a backup.
I am running Joomla 3.6.5 Stable. I cannot upgrade to Joomla 3.9 as the installation stops halfway through, also breaking the site. I have not tried upgrading to Joomla 4 yet.