Error after Joomla upgrade: Call to undefined method JEventDispatcher::getContent

[Alejandro]

A few users have reported the error below when editing listings after recent upgrades of both Joomla and JReviews.

Call to undefined method JEventDispatcher::getContent

The issue is not caused by JReviews, because it's also present when editing regular Joomla articles. So far I've narrowed it down to the Joomla editor "readmore button" plugin and disabling it allows the editor to work correctly.

I haven't experienced this issue on my own sites where the "readmore" button appears and works correctly inside the editor so I am not sure what's causing this problem on the affected sites.