[VOTE] 4.2.0 RC1

Hi Christo,

It looks like you did not close the RC1 Maven artifacts in Nexus.
All the 4.2.0 artifacts are from Jan 13 so presumably it's still RC0.

For example, see
https://repository.apache.org/content/groups/staging/org/apache/kafka/kafka_2.13/4.2.0/

Thanks,
Mickael

On Mon, Jan 19, 2026 at 5:28 PM Christo Lolov <christololov@gmail.com> wrote:
>
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
> * Docker release artifacts to be voted upon:
> apache/kafka:4.2.0-rc1
> apache/kafka-native:4.2.0-rc1
>
> * 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-rc1/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-rc1
>
> * Documentation:
> https://kafka.apache.org/42/documentation.html
>
> * Protocol:
> https://kafka.apache.org/42/protocol.html
>
> * Successful CI builds for the 4.2 branch:
> Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> at https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> There is a single failing test which I have since retried.
>
> System tests: I have setup my E2E environment and will share test
> results in the next ~24 hours.
> Chia-Ping has been very generous and helpful and is also running a
> parallel environment at
> https://jenkins.opensource4you.tw/job/kafka-e2e/636/
>
> * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> Docker Build Test Pipeline (JVM):
> https://github.com/apache/kafka/actions/runs/21135593072
> Docker Build Test Pipeline (Native):
> https://github.com/apache/kafka/actions/runs/21136272782
>
> Thanks,
> Christo
>
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