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Encountering an empty snapshot file means that that particular Kafka broker will treat all idempotent producers who produced prior to the offset of the snapshot file as expired. In the situation where a follower broker has rebuilt the auxiliary state from an empty snapshot, the leader broker has just gone down, some producer identifier have not produced since the offset of the empty snapshot, and the follower broker will become the leader, then those producer identifiers will be expired potentially resulting in duplicate records. Given that after the upgrade to from < 2.8 to 3.6 segments will start having an associated snapshot we are talking that the above situation also needs to happen in the narrow window during the upgrade.

Compatibility, Deprecation, and Migration Plan

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