Because of this difficulty (anyone, please?) I am beginning to think that I need to re-install RW 8, having first deleted all my addons - or, better, saved them somewhere else.
In which case, does anyone know how to see at a glance which addons each of my projects uses, please?
Surely I don’t have to open each project, see the spurious error messages, and make a manual list… so that I can re-install only those I need?
I’m kind of heading towards having to completely uninstall everything (I’ve been using RW since version 3!), launching each project in turn and only re-installing those (third party) add-ons which it complains about.
I’ve now successfully (uninstalled, ‘purged’ and then) re-installed RW 8.7; and moved my add-ons one by one into the ~/Library/Group Containers folder as ‘Managed by RapidWeaver’.
The fact that I no longer get such messages as these does appear to suggest that there is some way in which RW retains a list of (non-existent) addons… now looking forward to getting back to work