Quarkus 4 Beta 1 resets the Java stack for its next major release

Quarkus has released Quarkus 4.0.0.Beta1, the first beta of its next major version. The project plans a final release at the end of November and is explicitly asking extension maintainers to migrate now while application teams test their workloads and report problems.

That makes this more than a routine preview. Quarkus 4 changes the foundation beneath applications and extensions, so teams with custom extensions or tightly controlled runtime dependencies have a short validation window before the stable release.

A new baseline across the stack

Java 21 becomes the base Java version, with virtual threads taking a more central role. The networking layer moves to Netty 4.2 and Vert.x 5.x, while opt-in HTTP/3 support joins QUIC-related capabilities. Native transports, including epoll and io_uring, are supported in native executables as well as JVM deployments.

The persistence and API layers also take major-version steps. Quarkus 4 integrates Hibernate ORM 8, Jakarta Persistence 4.0, Jakarta Data 1.1, Jakarta REST 4 and Jackson 3. The release adds a dedicated JMS extension with Spring JMS compatibility, plus improved Kafka transaction support through @ExactlyOnce.

Observability is another focus. A new Observation API can generate metrics and traces through Micrometer and OpenTelemetry, and the Dev UI gains an observability dashboard intended to work in development mode without additional wiring.

What developers should do now

Extension maintainers should begin against Beta 1 rather than wait for the final release. The project’s Quarkus 4 migration guide is already substantial, including many configuration-key replacements alongside framework and dependency changes.

Application teams do not need to treat a beta as a production upgrade, but they should use it to expose compatibility work early. The highest-value checks are custom extensions, native-image builds, persistence mappings, JSON serialization, REST endpoints and network integrations. Build and runtime images also need to satisfy the Java 21 baseline.

The practical signal is clear: Quarkus 4 is now stable enough for migration testing, but not yet the final release. Teams that depend on extensions should test both the application and the extension ecosystem together, then send failures upstream while there is still time for fixes before late November.