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https://issues.apache.org/jira/browse/KAFKA-19704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18019872#comment-18019872
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Kuan Po Tseng commented on KAFKA-19704:
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Hi [~mithaj], the new 1MB segment.bytes constraint was introduced in 4.0, KIP:
https://cwiki.apache.org/confluence/x/FAqpEQ.
Perhaps you can try go back to the previous version, and use
bin/kafka-configs.sh alter the topic segment.bytes? (Make it >= 1MB)
> Kafka Broker Fails to Start After Upgrade to 4.1.0 Due to Invalid
> segment.bytes Configuration
> ---------------------------------------------------------------------------------------------
>
> Key: KAFKA-19704
> URL: https://issues.apache.org/jira/browse/KAFKA-19704
> Project: Kafka
> Issue Type: Bug
> Reporter: MithaJoseph
> Priority: Major
>
> After upgrading our Kafka brokers to version {*}4.1.0{*}, the broker fails to
> start due to a misconfigured topic-level {{segment.bytes}} setting. The new
> version enforces a *minimum value of 1MB (1048576 bytes)* for this
> configuration, and any value below this threshold causes the broker to
> terminate during startup.
> *Error Details:*
> **
>
> {code:java}
> [2025-09-12 14:39:51,285] ERROR Encountered fatal fault: Error starting
> LogManager (org.apache.kafka.server.fault.ProcessTerminatingFaultHandler)
> org.apache.kafka.common.config.ConfigException: Invalid value 75000 for
> configuration segment.bytes: Value must be at least 1048576 at
> org.apache.kafka.common.config.ConfigDef$Range.ensureValid(ConfigDef.java:989)
> ~[kafka-clients-4.1.0.jar:?]
>
> {code}
> In our setup, some topics were previously configured with a lower
> segment.bytes value (e.g., 75000), which was allowed in earlier Kafka
> versions but is now invalid.
> As a result Kafka broker cannot start, leading to downtime and
> unavailability.No snapshot file exists yet, so the {{kafka-metadata-shell}}
> tool cannot be used to patch the config offline.
> We would appreciate your guidance on the following:
> * Are there any supported methods from Kafka 4.1.0 to override or bypass
> this validation at startup to recover without losing data?
> * If not, is there a documented approach to fix such configuration issues
> when snapshots are not yet available?
>
>
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