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new 814ae38489 MINOR: Update docs for 4.2.1 "streams" broker side bug fix
(#880)
814ae38489 is described below
commit 814ae384897a78f0293a7d636b30305390d45b30
Author: gabriellafu <[email protected]>
AuthorDate: Mon Jun 15 12:16:04 2026 -0400
MINOR: Update docs for 4.2.1 "streams" broker side bug fix (#880)
Cf https://github.com/apache/kafka/pull/22525
---
content/en/42/getting-started/upgrade.md | 3 ++-
content/en/42/streams/developer-guide/streams-rebalance-protocol.md | 2 +-
content/en/42/streams/upgrade-guide.md | 2 +-
content/en/43/getting-started/upgrade.md | 3 ++-
content/en/43/streams/developer-guide/streams-rebalance-protocol.md | 2 +-
content/en/43/streams/upgrade-guide.md | 2 +-
6 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/content/en/42/getting-started/upgrade.md
b/content/en/42/getting-started/upgrade.md
index 25eaaa1ef6..c681e01797 100644
--- a/content/en/42/getting-started/upgrade.md
+++ b/content/en/42/getting-started/upgrade.md
@@ -31,6 +31,7 @@ type: docs
* Includes a fix for a critical deadlock in the
[KIP-932](https://cwiki.apache.org/confluence/x/4hA0Dw) Share Group path
([KAFKA-20505](https://issues.apache.org/jira/browse/KAFKA-20505)).
* Includes a fix for a rolling upgrade issue
([KAFKA-20322](https://issues.apache.org/jira/browse/KAFKA-20322)) that could
cause `UnsupportedVersionException` for clusters using transactional producers.
+ * Includes a fix for a critical broker-side bug in the offline migration
code for the Streams Rebalance Protocol
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)). Migrations
from classic to streams groups are now safe starting with 4.2.1.
## Upgrading to 4.2.0
@@ -42,7 +43,7 @@ type: docs
* The `--max-partition-memory-bytes` option in `kafka-console-producer` is
deprecated and will be removed in Kafka 5.0. Please use `--batch-size` instead.
* Queues for Kafka ([KIP-932](https://cwiki.apache.org/confluence/x/4hA0Dw))
is production-ready in Apache Kafka 4.2. This feature introduces a new kind of
group called share groups, as an alternative to consumer groups. Consumers in a
share group cooperatively consume records from topics, without assigning each
partition to just one consumer. Share groups also introduce per-record
acknowledgement and counting of delivery attempts. Use share groups in cases
where records are processed [...]
- * The Streams Rebalance Protocol
([KIP-1071](https://cwiki.apache.org/confluence/display/KAFKA/KIP-1071%3A+Streams+Rebalance+Protocol))
is now production-ready for its core feature set. This broker-driven
rebalancing system designed specifically for Kafka Streams applications
provides faster, more stable rebalances and better observability. For more
information about the supported feature set, usage, and migration, please refer
to the [Streams developer guide](/{version}/streams/develo [...]
+ * The Streams Rebalance Protocol
([KIP-1071](https://cwiki.apache.org/confluence/display/KAFKA/KIP-1071%3A+Streams+Rebalance+Protocol))
is now production-ready for its core feature set. This broker-driven
rebalancing system designed specifically for Kafka Streams applications
provides faster, more stable rebalances and better observability. For more
information about the supported feature set, usage, and migration, please refer
to the [Streams developer guide](/{version}/streams/develo [...]
* The `org.apache.kafka.common.header.internals.RecordHeader` class has been
updated to be read thread-safe. See
[KIP-1205](https://cwiki.apache.org/confluence/x/nYmhFg) for details. In other
words, each individual `Header` object within a `ConsumerRecord`'s `headers`
can now be safely read from multiple threads concurrently.
* The `org.apache.kafka.disallowed.login.modules` config was deprecated.
Please use the `org.apache.kafka.allowed.login.modules` instead.
* The `remote.log.manager.thread.pool.size` config was deprecated. Please
use the `remote.log.manager.follower.thread.pool.size` instead.
diff --git
a/content/en/42/streams/developer-guide/streams-rebalance-protocol.md
b/content/en/42/streams/developer-guide/streams-rebalance-protocol.md
index dc84182bf1..a097bfd4c5 100644
--- a/content/en/42/streams/developer-guide/streams-rebalance-protocol.md
+++ b/content/en/42/streams/developer-guide/streams-rebalance-protocol.md
@@ -254,4 +254,4 @@ Similarly, you can convert a streams group back to a
classic group by following
**Warning:** Online migration (migrating while the application is running) is
not available in this version. Plan for a maintenance window when migrating
between protocols.
-**Warning:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix will be targeted for a
future release.
+**Warning:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix is available in 4.2.1.
diff --git a/content/en/42/streams/upgrade-guide.md
b/content/en/42/streams/upgrade-guide.md
index e148f24295..a792997d3a 100644
--- a/content/en/42/streams/upgrade-guide.md
+++ b/content/en/42/streams/upgrade-guide.md
@@ -72,7 +72,7 @@ This release marks the General Availability for the core
functionality detailed
For more information about the feature set, design, usage and migration,
please refer to the [developer
guide](/{version}/streams/developer-guide/streams-rebalance-protocol).
-**Note:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix will be targeted for a
future release.
+**Note:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix is available in 4.2.1.
### Other changes
diff --git a/content/en/43/getting-started/upgrade.md
b/content/en/43/getting-started/upgrade.md
index d161dee2f6..2031ad877b 100644
--- a/content/en/43/getting-started/upgrade.md
+++ b/content/en/43/getting-started/upgrade.md
@@ -61,6 +61,7 @@ Note: Apache Kafka 4.3 only supports KRaft mode - ZooKeeper
mode has been remove
* Includes a fix for a critical deadlock in the
[KIP-932](https://cwiki.apache.org/confluence/x/4hA0Dw) Share Group path
([KAFKA-20505](https://issues.apache.org/jira/browse/KAFKA-20505)).
* Includes a fix for a rolling upgrade issue
([KAFKA-20322](https://issues.apache.org/jira/browse/KAFKA-20322)) that could
cause `UnsupportedVersionException` for clusters using transactional producers.
+ * Includes a fix for a critical broker-side bug in the offline migration
code for the Streams Rebalance Protocol
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)). Migrations
from classic to streams groups are now safe starting with 4.2.1.
## Upgrading to 4.2.0
@@ -81,7 +82,7 @@ Note: Apache Kafka 4.2 only supports KRaft mode - ZooKeeper
mode has been remove
* The `--max-partition-memory-bytes` option in `kafka-console-producer` is
deprecated and will be removed in Kafka 5.0. Please use `--batch-size` instead.
* Queues for Kafka ([KIP-932](https://cwiki.apache.org/confluence/x/4hA0Dw))
is production-ready in Apache Kafka 4.2. This feature introduces a new kind of
group called share groups, as an alternative to consumer groups. Consumers in a
share group cooperatively consume records from topics, without assigning each
partition to just one consumer. Share groups also introduce per-record
acknowledgement and counting of delivery attempts. Use share groups in cases
where records are processed [...]
- * The Streams Rebalance Protocol
([KIP-1071](https://cwiki.apache.org/confluence/display/KAFKA/KIP-1071%3A+Streams+Rebalance+Protocol))
is now production-ready for its core feature set. This broker-driven
rebalancing system designed specifically for Kafka Streams applications
provides faster, more stable rebalances and better observability. For more
information about the supported feature set, usage, and migration, please refer
to the [Streams developer guide](/{version}/streams/develo [...]
+ * The Streams Rebalance Protocol
([KIP-1071](https://cwiki.apache.org/confluence/display/KAFKA/KIP-1071%3A+Streams+Rebalance+Protocol))
is now production-ready for its core feature set. This broker-driven
rebalancing system designed specifically for Kafka Streams applications
provides faster, more stable rebalances and better observability. For more
information about the supported feature set, usage, and migration, please refer
to the [Streams developer guide](/{version}/streams/develo [...]
* The `org.apache.kafka.common.header.internals.RecordHeader` class has been
updated to be read thread-safe. See
[KIP-1205](https://cwiki.apache.org/confluence/x/nYmhFg) for details. In other
words, each individual `Header` object within a `ConsumerRecord`'s `headers`
can now be safely read from multiple threads concurrently.
* The `org.apache.kafka.disallowed.login.modules` config was deprecated.
Please use the `org.apache.kafka.allowed.login.modules` instead.
* The `remote.log.manager.thread.pool.size` config was deprecated. Please
use the `remote.log.manager.follower.thread.pool.size` instead.
diff --git
a/content/en/43/streams/developer-guide/streams-rebalance-protocol.md
b/content/en/43/streams/developer-guide/streams-rebalance-protocol.md
index dc84182bf1..a097bfd4c5 100644
--- a/content/en/43/streams/developer-guide/streams-rebalance-protocol.md
+++ b/content/en/43/streams/developer-guide/streams-rebalance-protocol.md
@@ -254,4 +254,4 @@ Similarly, you can convert a streams group back to a
classic group by following
**Warning:** Online migration (migrating while the application is running) is
not available in this version. Plan for a maintenance window when migrating
between protocols.
-**Warning:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix will be targeted for a
future release.
+**Warning:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix is available in 4.2.1.
diff --git a/content/en/43/streams/upgrade-guide.md
b/content/en/43/streams/upgrade-guide.md
index 8fd9f6193e..723bf23603 100644
--- a/content/en/43/streams/upgrade-guide.md
+++ b/content/en/43/streams/upgrade-guide.md
@@ -110,7 +110,7 @@ This release marks the General Availability for the core
functionality detailed
For more information about the feature set, design, usage and migration,
please refer to the [developer
guide](/{version}/streams/developer-guide/streams-rebalance-protocol).
-**Note:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix will be targeted for a
future release.
+**Note:** Due to a critical broker-side bug in the offline migration code
([KAFKA-20254](https://issues.apache.org/jira/browse/KAFKA-20254)), we
recommend against doing migrations from classic to streams groups in 4.2.0.
Newly created streams groups are not impacted. The fix is available in 4.2.1.
### Other changes
