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Note that followers will continue to write the records they receive from leaders without conversion. Since leaders will use v2 for new requests, replicating old data is the only case where v0 or v1 records may be written to disk after the upgrade to Apache Kafka 3.0.

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Apache Kafka 4.0

We will remove all write support for message formats v0 and v1 in Apache Kafka 4.0. Consumers will continue to support message formats v0 and v1. Similarly, brokers will still return message formats v0 and v1 with fetch v4 or higher.

Compatibility, Deprecation, and Migration Plan

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