Spring Could not find reactor-core-3.4.0-M1.jar (io.projectreactor:reactor-core:3.4.0-M1).

Could not find reactor-core-3.4.0-M1.jar (io.projectreactor:reactor-core:3.4.0-M1). Searched in the following locations: http://nexus.bsdn.org/content/groups/public/io/projectreactor/reactor-core/3.4.0-M1/reactor-core-3.4.0-M1.jar

Possible solution: - Declare repository providing the artifact, see the documentation at https://docs.gradle.org/current/userguide/declaring_repositories.html

Comment From: bclozel

Reactor and Spring projects Milestone versions are available on the Spring artifactory instance and are not synchronized to Maven Central: https://repo.spring.io/milestone

Please configure your Nexus artifact repository accordingly. Creating a new project on start.spring.io (using a Spring Boot milestone version) will provide the expected coordinates to resolve these artifacts.