damn being a minimalist, I'd forgotten I removed the EpubSplit and Quality Check plugins
I was able to remove the dead
Switch/create library… option in plugin configuration and add it back again.
There is a difference in the old and new json files, viz:
Sorry for the false alarm. Snookered by my own off break - the language switch
Maybe a msg could be popped if an item in the plugin's json can't be mapped to a valid target action.
BR