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new 164256f1270 KAFKA-20569 Add upgrade instructions for 4.2 and 4.3
(#22263)
164256f1270 is described below
commit 164256f12704619b3327f9452df5af6d6ff55a1a
Author: Mickael Maison <[email protected]>
AuthorDate: Mon May 18 14:55:35 2026 +0200
KAFKA-20569 Add upgrade instructions for 4.2 and 4.3 (#22263)
I reused the format we used for 4.0
Reviewers: Murali Basani <[email protected]>, Chia-Ping Tsai
<[email protected]>
---
docs/getting-started/upgrade.md | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/docs/getting-started/upgrade.md b/docs/getting-started/upgrade.md
index 7c676ffe7fa..145960a483a 100644
--- a/docs/getting-started/upgrade.md
+++ b/docs/getting-started/upgrade.md
@@ -39,6 +39,14 @@ type: docs
### Upgrading Servers to 4.3.0 from any version 3.3.x through 4.2.0
+Note: Apache Kafka 4.3 only supports KRaft mode - ZooKeeper mode has been
removed. As such, **broker upgrades to 4.3.0 (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 4.3.x. Clusters in ZooKeeper mode have to be [migrated to KRaft
mode](/43/operations/kraft/#zookeeper [...]
+
+**For a rolling upgrade:**
+
+ 1. Upgrade the brokers one at a time: shut down the broker, update the code,
and restart it. Once you have done so, the brokers will be running the latest
version and you can verify that the cluster's behavior and performance meet
expectations.
+ 2. Once the cluster's behavior and performance have been verified, finalize
the upgrade by running `bin/kafka-features.sh --bootstrap-server localhost:9092
upgrade --release-version 4.3`
+ 3. Note that cluster metadata downgrade is not supported in this version
since it has metadata changes. Every
[MetadataVersion](https://github.com/apache/kafka/blob/trunk/server-common/src/main/java/org/apache/kafka/server/common/MetadataVersion.java)
has a boolean parameter that indicates if there are metadata changes (i.e.
`IBP_4_3_IV0(30, "4.3", "IV0", true)` means this version has metadata changes).
Given your current and target versions, a downgrade is only possible if there
are n [...]
+
### Notable changes in 4.3.0
* `kafka-configs.sh --alter --delete-config` no longer requires the
specified config keys to exist on the target resource. Previously, attempting
to delete a non-existent config key raised an `InvalidConfigurationException`.
The deletion is now a no-op when the key does not exist, which allows managing
configs for offline brokers via `--bootstrap-controller`. For further details,
please refer to
[KAFKA-20506](https://issues.apache.org/jira/browse/KAFKA-20506).
@@ -59,6 +67,15 @@ type: docs
### Upgrading Servers to 4.2.0 from any version 3.3.x through 4.1.x
+Note: Apache Kafka 4.2 only supports KRaft mode - ZooKeeper mode has been
removed. As such, **broker upgrades to 4.2.0 (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 4.2.x. Clusters in ZooKeeper mode have to be [migrated to KRaft
mode](/43/operations/kraft/#zookeeper [...]
+
+**For a rolling upgrade:**
+
+ 1. Upgrade the brokers one at a time: shut down the broker, update the code,
and restart it. Once you have done so, the brokers will be running the latest
version and you can verify that the cluster's behavior and performance meet
expectations.
+ 2. Once the cluster's behavior and performance have been verified, finalize
the upgrade by running `bin/kafka-features.sh --bootstrap-server localhost:9092
upgrade --release-version 4.2`
+ 3. Note that cluster metadata downgrade is supported in this version since
it has no metadata changes. Every
[MetadataVersion](https://github.com/apache/kafka/blob/trunk/server-common/src/main/java/org/apache/kafka/server/common/MetadataVersion.java)
has a boolean parameter that indicates if there are metadata changes (i.e.
`IBP_4_2_IV1(29, "4.2", "IV1", false)` means this version has no metadata
changes). Given your current and target versions, a downgrade is only possible
if there ar [...]
+
+
* If you wish to use share groups in a cluster with fewer than 3 brokers,
you must set the broker configurations
`share.coordinator.state.topic.replication.factor` and
`share.coordinator.state.topic.min.isr` to 1 before you start using share
groups. This is because share groups make use of a new internal topic called
`__share_group_state` which is automatically created when you first use share
groups. In common with the other internal topics, the default configuration
uses 3 replicas a [...]
### Notable changes in 4.2.0
