to 4.0.0 (and higher) require KRaft mode and
    the software and metadata versions must be at least 3.3.x</b> (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 <a href="/{{version}}/documentation.html#kraft_zk_migration">migrated to KRaft mode</a> before they can be upgraded to 4.0.x.
</p>

<p><b>For a rolling upgrade:</b></p>

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