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- Broker must be upgraded to 2.5 first.
- Upgrade the stream application binary and choose to set UPGRADE_FROM_CONFIG config to 2.4 5 (note that 2.5 refers to the Streams version, not the broker version) or lower and set PROCESSING_GUARATNEE to "exaclty_once_beta". Do the first rolling bounce, and make sure the group is stable with every instance on 2.6 binary.
- Remove/unset UPGRADE_FROM_CONFIG, in order to point the application to actual Kafka client version. Do a second rolling bounce and now the application officially starts using new thread producer for EOS.
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