Hi Christo, I’ve done the following: * Downloaded the binary release artifacts * Created a cluster, basic Quickstart tests, checked API versions and features * Downloaded the 4.2 documentation and ran it locally * Checked the javadoc for expected 4.2 content
I found one issue. When I navigated to any of the config pages in the docs, such as …/42/configuration/consumer-configs/, I find that the list of configs is missing. As I understand it, when we had HTML docs, the tooling would call the main() method of the ConsumerConfigs class to generate an HTML representation of the configs for inclusion in the docs. I’m not sure whether that’s missing for markdown, or just missing because this is an RC. Thanks, Andrew > On 27 Jan 2026, at 15:50, Christo Lolov <[email protected]> wrote: > > Hello Kafka users, developers and client-developers, > > This is the RC2 candidate for release of Apache Kafka 4.2.0. > > This release has many exciting changes: > * Kafka Queues (Share Groups) is now production-ready with new > features like the RENEW acknowledgement type for extended processing > times, adaptive batching for coordinators, and comprehensive lag > metrics. > * Kafka Streams brings the server-side rebalance protocol to GA with a > limited feature set, adds dead letter queue support in exception > handlers, introduces anchored wall-clock punctuation for deterministic > scheduling, and gives users full control over whether to send a leave > group request on closing. > * This release also delivers significant improvements to consistency > and observability: CLI tools now feature standardized arguments like > --bootstrap-server across all tools, metric naming has been corrected > to follow the kafka.COMPONENT convention, and new idle ratio metrics > provide better visibility into controller and MetadataLoader > performance. > * Security is enhanced with a new allowlist connector client > configuration override policy, while thread-safety improvements to > RecordHeader eliminate concurrency risks. > * Additional highlights include external schema support in > JsonConverter for reduced message sizes, dynamic configuration for > remote log manager thread pools, and rack ID exposure in the Admin API > for consumer and share group members. > > Release notes for the 4.2.0 release: > https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc2/RELEASE_NOTES.html > > *** Please download, test and vote by Friday, January 30, 5pm UTC > > Kafka's KEYS file containing PGP keys we use to sign the release: > https://kafka.apache.org/KEYS > > * Release artifacts to be voted upon (source and binary): > https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc2/ > > * Docker release artifacts to be voted upon: > apache/kafka:4.2.0-rc2 > apache/kafka-native:4.2.0-rc2 > > * Maven artifacts to be voted upon: > https://repository.apache.org/content/groups/staging/org/apache/kafka/ > > * Javadoc: > https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc2/javadoc/index.html > > * Tag to be voted upon (off 4.2 branch) is the 4.2.0 tag: > https://github.com/apache/kafka/releases/tag/4.2.0-rc2 > > * Documentation: > * Protocol: > https://github.com/apache/kafka-site/pull/785 > > * Successful CI builds for the 4.2 branch: > Unit/integration tests: The ongoing build for the 4.2.0-rc2 tag can be found > at https://github.com/apache/kafka/actions/runs/21398201956/job/61611167690 > > System tests: I have started the tests in my environment and will share test > results in the next ~24 hours. > > * Successful Docker Image Github Actions Pipeline for 4.2 branch: > Docker Build Test Pipeline (JVM): > https://github.com/apache/kafka/actions/runs/21402423697 > Docker Build Test Pipeline (Native): > https://github.com/apache/kafka/actions/runs/21398799585 > > Thanks, > Christo
