apache/iceberg · error · UnsupportedOperationException

The method start(Catalog, IcebergSinkConfig…

Error message

The method start(Catalog, IcebergSinkConfig, SinkTaskContext) is deprecated and will be removed in 2.0.0. Use start(Catalog, IcebergSinkConfig, SinkTaskContext, Collection<TopicPartition>) instead.

What it means

CommitterImpl implements the deprecated 3-argument Committer.start method and deliberately throws UnsupportedOperationException to force migration to the 4-argument overload that receives the currently assigned TopicPartitions. The deprecated entry point cannot work correctly with the partition-based worker lifecycle the sink now uses. This is a hard-stop guard, not a graceful deprecation.

Solutions

1. Call the 4-argument overload start(Catalog, IcebergSinkConfig, SinkTaskContext, Collection<TopicPartition>) passing the partitions currently assigned to the task.
2. If invoked indirectly by the Connect framework, upgrade the Iceberg sink connector (and Kafka Connect runtime) to versions that agree on the new interface.
3. If you maintain a wrapper or subclass of CommitterImpl, forward to the new overload instead of the deprecated one.

Example fix

// before
committer.start(catalog, sinkConfig, sinkTaskContext);

// after
committer.start(catalog, sinkConfig, sinkTaskContext, context.assignment());

// Java
if (partitions == null) {
  throw new IllegalArgumentException("partitions collection required: use the 4-arg start overload");
}
committer.start(catalog, sinkConfig, sinkTaskContext, partitions);

try { committer.start(catalog, cfg, ctx, partitions); } catch (UnsupportedOperationException e) { throw new IllegalStateException("Connector/framework version mismatch on Committer API", e); }

When it happens

Trigger: Kafka Connect's worker calls the old Committer.start(Catalog, IcebergSinkConfig, SinkTaskContext) overload — i.e. running an Iceberg sink connector version whose Committer interface still exposes the 3-arg start against this implementation, typically a version-mismatch between connector code and Connect framework or an externally constructed Committer invoking the legacy method.

Common situations: Upgrading the Iceberg Kafka Connect sink while a custom or patched Connect runtime still binds to the legacy SenderTask/Committer signatures; building a custom channel implementation that calls start() without the assigned partitions collection.

Understand the failure class

Background: "is deprecated and will be removed" — deprecation warnings for old API names, keywords, and options, and how to migrate before the removal release — this error's family across 29 libraries.

Related errors

• The method stop() is deprecated and will be removed in…
• Altering schema is not supported in the old alterTable API…
• Cannot convert type
• Incremental scan is not supported
• Server does not support endpoint

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/1e1405ca34dc92d3. Report an issue: GitHub.

Appendix: source

Thrown at kafka-connect/kafka-connect/src/main/java/org/apache/iceberg/connect/channel/CommitterImpl.java:135

    }

    return containsFirst;
  }

  @VisibleForTesting
  TopicPartition findFirstTopicPartition(Collection<MemberDescription> members) {
    return members.stream()
        .flatMap(member -> member.assignment().topicPartitions().stream())
        .min(new TopicPartitionComparator())
        .orElse(null);
  }

  @Override
  public void start(
      Catalog icebergCatalog,
      IcebergSinkConfig icebergSinkConfig,
      SinkTaskContext sinkTaskContext) {
    throw new UnsupportedOperationException(
        "The method start(Catalog, IcebergSinkConfig, SinkTaskContext) is deprecated and will be removed in 2.0.0. "
            + "Use start(Catalog, IcebergSinkConfig, SinkTaskContext, Collection<TopicPartition>) instead.");
  }

  @Override
  public void open(
      Catalog icebergCatalog,
      IcebergSinkConfig icebergSinkConfig,
      SinkTaskContext sinkTaskContext,
      Collection<TopicPartition> addedPartitions) {
    initialize(icebergCatalog, icebergSinkConfig, sinkTaskContext);
    if (hasLeaderPartition(addedPartitions)) {
      LOG.info("Committer {} received leader partition. Starting Coordinator.", taskId);
      startCoordinator();
    }
  }

  @Override

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