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chia7712 pushed a commit to branch 4.0
in repository https://gitbox.apache.org/repos/asf/kafka.git
The following commit(s) were added to refs/heads/4.0 by this push:
new 3d12c2c4da4 MINOR: Fix zk2kraft page broken link (#21284)
3d12c2c4da4 is described below
commit 3d12c2c4da4f4a5f8ad2b310aed737cda9d0c0d7
Author: Ken Huang <[email protected]>
AuthorDate: Mon Jan 12 11:58:44 2026 +0800
MINOR: Fix zk2kraft page broken link (#21284)
https://github.com/apache/kafka/pull/21270 for 4.0 branch
Reviewers: Chia-Ping Tsai <[email protected]>
---
docs/getting-started/upgrade.md | 12 ++++++------
docs/getting-started/zk2kraft.md | 2 +-
docs/operations/kraft.md | 2 +-
docs/streams/developer-guide/dsl-api.md | 2 +-
docs/streams/upgrade-guide.md | 4 ++--
5 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/docs/getting-started/upgrade.md b/docs/getting-started/upgrade.md
index 5ef3fa86567..797f3a92f57 100644
--- a/docs/getting-started/upgrade.md
+++ b/docs/getting-started/upgrade.md
@@ -33,13 +33,13 @@ type: docs
**For a rolling upgrade:**
1. Upgrade the clients one at a time: shut down the client, update the code,
and restart it.
- 2. Clients (including Streams and Connect) must be on version 2.1 or higher
before upgrading to 4.0. Many deprecated APIs were removed in Kafka 4.0. For
more information about the compatibility, please refer to the [compatibility
matrix](/40/documentation/compatibility.html) or
[KIP-1124](https://cwiki.apache.org/confluence/x/y4kgF).
+ 2. Clients (including Streams and Connect) must be on version 2.1 or higher
before upgrading to 4.0. Many deprecated APIs were removed in Kafka 4.0. For
more information about the compatibility, please refer to the [compatibility
matrix](/40/getting-started/compatibility) or
[KIP-1124](https://cwiki.apache.org/confluence/x/y4kgF).
### Upgrading Servers to 4.0.1 from any version 3.3.x through 3.9.x
-Note: Apache Kafka 4.0 only supports KRaft mode - ZooKeeper mode has been
removed. As such, **broker upgrades to 4.0.0 (and higher) require KRaft mode
and the software and metadata versions must be at least 3.3.x** (the first
version when KRaft mode was deemed production ready). For clusters in KRaft
mode with versions older than 3.3.x, we recommend upgrading to 3.9.x before
upgrading to 4.0.x. Clusters in ZooKeeper mode have to be [migrated to KRaft
mode](/40/documentation.html#kraft_zk [...]
+Note: Apache Kafka 4.0 only supports KRaft mode - ZooKeeper mode has been
removed. As such, **broker upgrades to 4.0.0 (and higher) require KRaft mode
and the software and metadata versions must be at least 3.3.x** (the first
version when KRaft mode was deemed production ready). For clusters in KRaft
mode with versions older than 3.3.x, we recommend upgrading to 3.9.x before
upgrading to 4.0.x. Clusters in ZooKeeper mode have to be [migrated to KRaft
mode](/40/operations/kraft/#zookeeper [...]
**For a rolling upgrade:**
@@ -52,14 +52,14 @@ Note: Apache Kafka 4.0 only supports KRaft mode - ZooKeeper
mode has been remove
### Notable changes in 4.0.1
* The filename for rotated `state-change.log` files has been updated from
`stage-change.log.[date]` to `state-change.log.[date]` in the log4j2.yaml
configuration file. See
[KAFKA-19576](https://issues.apache.org/jira/browse/KAFKA-19576) for details.
- * Kafka Streams include a critical fix to upgrade from
`KStreams#transformValues()` (removed with 4.0.0 release) to
`KStreams#processValues()`. For more details, see the [migration
guide](/40/documentation/streams/developer-guide/dsl-api.html#transformers-removal-and-migration-to-processors).
+ * Kafka Streams include a critical fix to upgrade from
`KStreams#transformValues()` (removed with 4.0.0 release) to
`KStreams#processValues()`. For more details, see the [migration
guide](/40/streams/developer-guide/dsl-api/#transformers-removal-and-migration-to-processors).
### Notable changes in 4.0.0
* Old protocol API versions have been removed. Users should ensure brokers
are version 2.1 or higher before upgrading Java clients (including Connect and
Kafka Streams which use the clients internally) to 4.0. Similarly, users should
ensure their Java clients (including Connect and Kafka Streams) version is 2.1
or higher before upgrading brokers to 4.0. Finally, care also needs to be taken
when it comes to kafka clients that are not part of Apache Kafka, please see
[KIP-896](https://cw [...]
- * Apache Kafka 4.0 only supports KRaft mode - ZooKeeper mode has been
removed. About version upgrade, check [Upgrading to 4.0.1 from any version
3.3.x through 3.9.x](/40/documentation.html#upgrade_4_0_1) for more info.
+ * Apache Kafka 4.0 only supports KRaft mode - ZooKeeper mode has been
removed. About version upgrade, check [Upgrading to 4.0.1 from any version
3.3.x through
3.9.x](/40/getting-started/upgrade/#upgrading-servers-to-401-from-any-version-33x-through-39x)
for more info.
* Apache Kafka 4.0 ships with a brand-new group coordinator implementation
(See
[here](https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=217387038#KIP848:TheNextGenerationoftheConsumerRebalanceProtocol-GroupCoordinator)).
Functionally speaking, it implements all the same APIs. There are reasonable
defaults, but the behavior of the new group coordinator can be tuned by setting
the configurations with prefix `group.coordinator`.
* The Next Generation of the Consumer Rebalance Protocol
([KIP-848](https://cwiki.apache.org/confluence/display/KAFKA/KIP-848%3A+The+Next+Generation+of+the+Consumer+Rebalance+Protocol))
is now Generally Available (GA) in Apache Kafka 4.0. The protocol is
automatically enabled on the server when the upgrade to 4.0 is finalized. Note
that once the new protocol is used by consumer groups, the cluster can only
downgrade to version 3.4.1 or newer. Check
[here](/40/documentation.html#consume [...]
* Transactions Server Side Defense
([KIP-890](https://cwiki.apache.org/confluence/display/KAFKA/KIP-890%3A+Transactions+Server-Side+Defense))
brings a strengthened transactional protocol to Apache Kafka 4.0. The new and
improved transactional protocol is enabled when the upgrade to 4.0 is
finalized. When using 4.0 producer clients, the producer epoch is bumped on
every transaction to ensure every transaction includes the intended messages
and duplicates are not written as part of the n [...]
@@ -139,9 +139,9 @@ Note: Apache Kafka 4.0 only supports KRaft mode - ZooKeeper
mode has been remove
* The `all()` method was removed from the
`org.apache.kafka.clients.admin.DescribeTopicsResult`. Please use
`allTopicNames()` instead.
* **Kafka Streams**
* All public API, deprecated in Apache Kafka 3.6 or an earlier release,
have been removed, with the exception of `JoinWindows.of()` and
`JoinWindows#grace()`. See
[KAFKA-17531](https://issues.apache.org/jira/browse/KAFKA-17531) for details.
- * The most important changes are highlighted in the [Kafka Streams
upgrade
guide](/40/documentation/streams/upgrade-guide.html#streams_api_changes_400).
+ * The most important changes are highlighted in the [Kafka Streams
upgrade guide](/40/streams/upgrade-guide/#streams-api-changes-in-400).
* For a full list of changes, see
[KAFKA-12822](https://issues.apache.org/jira/browse/KAFKA-12822).
- * If you are using `KStream#transformValues()` which was removed with
Apache Kafka 4.0.0 release, and you need to rewrite your program to use
`KStreams#processValues()` instead, pay close attention to the [migration
guide](/40/documentation/streams/developer-guide/dsl-api.html#transformers-removal-and-migration-to-processors).
+ * If you are using `KStream#transformValues()` which was removed with
Apache Kafka 4.0.0 release, and you need to rewrite your program to use
`KStreams#processValues()` instead, pay close attention to the [migration
guide](/40/streams/developer-guide/dsl-api/#transformers-removal-and-migration-to-processors).
* Other changes:
* The minimum Java version required by clients and Kafka Streams
applications has been increased from Java 8 to Java 11 while brokers, connect
and tools now require Java 17. See
[KIP-750](https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=181308223)
and
[KIP-1013](https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=284789510)
for more details.
* Java 23 support has been added in Apache Kafka 4.0
diff --git a/docs/getting-started/zk2kraft.md b/docs/getting-started/zk2kraft.md
index 3ef7d5017a4..7af067bf970 100644
--- a/docs/getting-started/zk2kraft.md
+++ b/docs/getting-started/zk2kraft.md
@@ -30,7 +30,7 @@ type: docs
# Removed ZooKeeper Features
-This section documents differences in behavior between KRaft mode and
ZooKeeper mode. Specifically, several configurations, metrics and features have
changed or are no longer required in KRaft mode. To migrate an existing cluster
from ZooKeeper mode to KRaft mode, please refer to the [ZooKeeper to KRaft
Migration](/39/documentation.html#kraft_zk_migration) section.
+This section documents differences in behavior between KRaft mode and
ZooKeeper mode. Specifically, several configurations, metrics and features have
changed or are no longer required in KRaft mode. To migrate an existing cluster
from ZooKeeper mode to KRaft mode, please refer to the [ZooKeeper to KRaft
Migration](/39/operations/kraft/#zookeeper-to-kraft-migration) section.
## Configurations
diff --git a/docs/operations/kraft.md b/docs/operations/kraft.md
index fbdc5175052..dc87bdecacc 100644
--- a/docs/operations/kraft.md
+++ b/docs/operations/kraft.md
@@ -239,4 +239,4 @@ The kafka-metadata-shell.sh tool can be used to
interactively inspect the state
## ZooKeeper to KRaft Migration
-In order to migrate from ZooKeeper to KRaft you need to use a bridge release.
The last bridge release is Kafka 3.9. See the [ZooKeeper to KRaft Migration
steps](/39/documentation/#kraft_zk_migration) in the 3.9 documentation.
+In order to migrate from ZooKeeper to KRaft you need to use a bridge release.
The last bridge release is Kafka 3.9. See the [ZooKeeper to KRaft Migration
steps](/39/operations/kraft/#zookeeper-to-kraft-migration) in the 3.9
documentation.
diff --git a/docs/streams/developer-guide/dsl-api.md
b/docs/streams/developer-guide/dsl-api.md
index 874300d6c74..0fe0438c846 100644
--- a/docs/streams/developer-guide/dsl-api.md
+++ b/docs/streams/developer-guide/dsl-api.md
@@ -4994,7 +4994,7 @@ Stateful
-Transformers removal and migration to processors
+### Transformers removal and migration to processors
As of Kafka 4.0, several deprecated methods in the Kafka Streams API, such as
`transform`, `flatTransform`, `transformValues`, `flatTransformValues`, and
`process` have been removed. These methods have been replaced with the more
versatile Processor API. This guide provides detailed steps for migrating
existing code to use the new Processor API and explains the benefits of the
changes.
diff --git a/docs/streams/upgrade-guide.md b/docs/streams/upgrade-guide.md
index 3160902773c..78cffe5f4c0 100644
--- a/docs/streams/upgrade-guide.md
+++ b/docs/streams/upgrade-guide.md
@@ -74,7 +74,7 @@ In this release, eos-v1 (Exactly Once Semantics version 1) is
no longer supporte
* [Old processor APIs](https://issues.apache.org/jira/browse/KAFKA-12829)
* [KStream#through() in both Java and
Scala](https://issues.apache.org/jira/browse/KAFKA-12823)
* ["transformer" methods and classes in both Java and
Scala](https://issues.apache.org/jira/browse/KAFKA-16339)
- * migrating from `KStreams#transformValues()` to
`KStreams.processValues()` might not be safe due to
[KAFKA-19668](https://issues.apache.org/jira/browse/KAFKA-19668). Please refer
to the [migration
guide](/40/documentation/streams/developer-guide/dsl-api.html#transformers-removal-and-migration-to-processors)
for more details.
+ * migrating from `KStreams#transformValues()` to
`KStreams.processValues()` might not be safe due to
[KAFKA-19668](https://issues.apache.org/jira/browse/KAFKA-19668). Please refer
to the [migration
guide](/40/streams/developer-guide/dsl-api/#transformers-removal-and-migration-to-processors)
for more details.
* [kstream.KStream#branch in both Java and
Scala](https://issues.apache.org/jira/browse/KAFKA-12824)
* [builder methods for
Time/Session/Join/SlidingWindows](https://issues.apache.org/jira/browse/KAFKA-16332)
*
[KafkaStreams#setUncaughtExceptionHandler()](https://issues.apache.org/jira/browse/KAFKA-12827)
@@ -223,7 +223,7 @@ Kafka Streams does not send a "leave group" request when an
instance is closed.
* `KStream<KOut,VOut> KStream.process(ProcessorSupplier, ...)`
* `KStream<K,VOut> KStream.processValues(FixedKeyProcessorSupplier, ...)`
-Both new methods have multiple overloads and return a `KStream` instead of
`void` as the deprecated `process()` methods did. In addition,
`FixedKeyProcessor`, `FixedKeyRecord`, `FixedKeyProcessorContext`, and
`ContextualFixedKeyProcessor` are introduced to guard against disallowed key
modification inside `processValues()`. Furthermore, `ProcessingContext` is
added for a better interface hierarchy. **CAUTION:** The newly added
`KStream.processValues()` method introduced a regression bug ( [...]
+Both new methods have multiple overloads and return a `KStream` instead of
`void` as the deprecated `process()` methods did. In addition,
`FixedKeyProcessor`, `FixedKeyRecord`, `FixedKeyProcessorContext`, and
`ContextualFixedKeyProcessor` are introduced to guard against disallowed key
modification inside `processValues()`. Furthermore, `ProcessingContext` is
added for a better interface hierarchy. **CAUTION:** The newly added
`KStream.processValues()` method introduced a regression bug ( [...]
Emitting a windowed aggregation result only after a window is closed is
currently supported via the `suppress()` operator. However, `suppress()` uses
an in-memory implementation and does not support RocksDB. To close this gap,
[KIP-825](https://cwiki.apache.org/confluence/display/KAFKA/KIP-825%3A+introduce+a+new+API+to+control+when+aggregated+results+are+produced)
introduces "emit strategies", which are built into the aggregation operator
directly to use the already existing RocksDB stor [...]
