Hi Christo,
* Verified signatures and checksums for source, binary, and site-docs tarballs
* Verified LICENSE file exists and is correct
* Built from source with JDK 21 (built in ~20 min)
* Ran the quickstart (KRaft mode) - produce/consume working
* Tested Docker images (both JVM and native)
* Reviewed Javadoc and release notes
* Verified Maven staging artifacts with correct dates (Feb 10, 2026)
* Validated KIP-1071:
- Tested wordcount app using group.protocol=streams
- kafka-streams-groups.sh working with --verbose output
- Dynamic config for standby replicas working
Issue found (non-blocking):
* Binary distribution NOTICE file has "Copyright 2021" instead of
"Copyright 2026"
(source tarball has the correct year)
+1 (binding)
Cheers,
Lucas
On Thu, Feb 12, 2026 at 12:55 PM Andrew Schofield <[email protected]> wrote:
>
> Hi Christo,
> I did the following to validate the release.
>
> * Checked the readme
> * Downloaded the binary release
> * Created a cluster
> * Checked feature levels and supported broker APIs
> * Performed basic testing of share groups
> * Checked Javadoc for new 4.2 content
> * Tested the Docker image with Spring Boot
>
> +1 (non-binding)
>
> Thanks,
> Andrew
>
> On 2026/02/10 15:27:09 Christo Lolov wrote:
> > Hello Kafka users, developers and client-developers,
> >
> > This is the RC4 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-rc4/RELEASE_NOTES.html
> >
> > *** Please download, test and vote by Friday, February 13, 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-rc4/
> >
> > * Docker release artifacts to be voted upon:
> > apache/kafka:4.2.0-rc4
> > apache/kafka-native:4.2.0-rc4
> >
> > * 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-rc4/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-rc4
> >
> > * Documentation:
> > * Protocol:
> > https://github.com/apache/kafka-site/pull/785
> >
> > * Successful CI builds for the 4.2 branch:
> > Unit/integration tests:
> > https://github.com/apache/kafka/actions/runs/21860071096
> > 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/21861574007
> > Docker Build Test Pipeline (Native):
> > https://github.com/apache/kafka/actions/runs/21861786570
> >
> > Thanks,
> > Christo
> >
