I am seeing an error (screenshot below) when trying to access the CB AcyMailing Plugin (Version 2.50).
I have a site with J3 that had AcyMailing 5.x. I have installed their latest version (V9.x) to prepare for the J4 Migration so I don't know if it's related to having both V5 and V9 on the site. (I plan to remove V5)
I also have CBSubs AcyMailing installed (Version 4.70) and that looks okay.
Perhaps I need to remove AcyMailing 5.x? I'm not sure how CB/CBSubs knows which version to "talk" to.