The Neo4j team has published the second milestone release of Neo4j Enterprise Edition 4.0, which is a pre-alpha version that includes some upcoming features for testing purposes. This release is not ready for production and may contain issues. It can be downloaded from the Neo4j Desktop or Download Center and is commercially licensed under the Neo4j Pre-Release Agreement. The new features include reactive drivers, back pressure and flow control, support for multiple databases, fine-grained security with a schema-based model, role and user management, system database, neo4j:// scheme, new Spring Boot starter, SDN/RX, index population algorithm, index key size, and improved space reclaim. The team invites users to try out the release, provide feedback, and contribute to its improvement.