I get what you mean re: versions, though it might take a couple of months to migrate all our grails 3 service to grails 4 - I guess I'm trying to avoid having to maintain those two versions at the same time, for some time. Yes it seems like as I'm building the Grails 4 app with Gradle 5, and it is also trying to build the grails 3 plugin from the workspace (via the settings.gradle include), that it just can't build that Grails 3 plugin using gradle 5 (due to deprecated / removed code)