error message

I have Content Views Pro installed, although it’s a little older and I’m beyond the support window. A few WP updates ago, I got a message in my dashboard that Content Views Pro requires an update of Content Views (free), and went to update that. It produced this error: “There has been a critical error on this website. Please check your site admin email inbox for instructions.”

All of my other plugins update fine. As far as I can tell, there’s actually nothing wrong with the site overall. But the Content Views entry in the plugins list on the dashboard now perpetually displays this error message instead of all the normal stuff (i.e. “update,” “deactivate,” etc. don’t display), and if I try to click on the link in the notice that the thing needs updating, that should go to the plugin’s listing (like where you would install it if you don’t have it), I get a screen with that same message instead of the plugin page.