apache/kafka · error · IllegalArgumentException

Cannot create a new partition reassignment without any repli

Error message

Cannot create a new partition reassignment without any replicas

What it means

Thrown by the NewPartitionReassignment constructor when targetReplicas is null or empty. A reassignment must specify at least one replica (broker id), so an empty list is meaningless and rejected immediately rather than sent to the controller.

Source

Thrown at clients/src/main/java/org/apache/kafka/clients/admin/NewPartitionReassignment.java:37

import org.apache.kafka.common.annotation.InterfaceAudience;

import java.util.List;
import java.util.Map;

/**
 * A new partition reassignment, which can be applied via {@link AdminClient#alterPartitionReassignments(Map, AlterPartitionReassignmentsOptions)}.
 */
@InterfaceAudience.Public
public class NewPartitionReassignment {
    private final List<Integer> targetReplicas;

    /**
     * @throws IllegalArgumentException if no replicas are supplied
     */
    public NewPartitionReassignment(List<Integer> targetReplicas) {
        if (targetReplicas == null || targetReplicas.isEmpty())
            throw new IllegalArgumentException("Cannot create a new partition reassignment without any replicas");
        this.targetReplicas = List.copyOf(targetReplicas);
    }

    public List<Integer> targetReplicas() {
        return targetReplicas;
    }
}

View on GitHub (pinned to c31c9215e1)

Solutions

1. To cancel an ongoing reassignment, pass null as the value for that partition in the alterPartitionReassignments map instead of an empty NewPartitionReassignment
2. Ensure targetReplicas contains at least one valid broker id before constructing the object
3. Validate the computed replica list is non-empty and log the inputs when it is unexpectedly empty

Example fix

// before
admin.alterPartitionReassignments(Map.of(
    tp, new NewPartitionReassignment(List.of()))); // throws

// after - assign replicas
admin.alterPartitionReassignments(Map.of(
    tp, new NewPartitionReassignment(List.of(1, 2, 3))));
// after - cancel an existing reassignment
admin.alterPartitionReassignments(Map.of(tp, null));

List<Integer> targetReplicas = ...;
if (targetReplicas == null || targetReplicas.isEmpty()) {
    throw new IllegalArgumentException(
        "targetReplicas must be a non-null, non-empty list of broker ids");
}
// Optional: also reject unknown/negative broker ids before constructing.
if (targetReplicas.stream().anyMatch(id -> id == null || id < 0)) {
    throw new IllegalArgumentException("targetReplicas contains null or negative broker id");
}
NewPartitionReassignment reassignment = new NewPartitionReassignment(targetReplicas);

static boolean isValidReassignment(List<Integer> replicas) {
    return replicas != null && !replicas.isEmpty()
        && replicas.stream().noneMatch(id -> id == null || id < 0);
}

try {
    NewPartitionReassignment reassignment = new NewPartitionReassignment(targetReplicas);
} catch (IllegalArgumentException e) {
    // No replicas supplied; this is a config/input error.
    // Surface it to the operator or skip the reassignment for this partition.
    log.error("Cannot build reassignment: {}", e.getMessage());
}

When it happens

Trigger: Constructing new NewPartitionReassignment(Collections.emptyList()) or passing a null list, then using it in Admin.alterPartitionReassignments. Also triggered when a list built from filtering or partitioning happens to contain zero broker ids at runtime.

Common situations: Building the replica list dynamically from a config or discovery call that returned nothing; passing an empty list to signal cancellation of a reassignment (the API uses null in the value of the alterPartitionReassignments map for cancellation, not an empty NewPartitionReassignment); off-by-one or empty ranges when computing target brokers.

Related errors

• Invalid empty members has been provided
• Offsets for consumer group '{groupId}' were not requested.
• List Offsets for partition "{partition}" was not attempted
• Group ID not found: {groupId}
• The method: memberResult is not applicable in 'removeAll' mo

AI-assisted analysis of apache/kafka@c31c9215e1 (2026-08-03). Data as JSON: /data/errors/dd04380d03a0988b.json. Report an issue: GitHub.