apache/pulsar · error · RestException

Desired partitions can't be greater than the maximum…

Error message

Desired partitions %s can't be greater than the maximum partitions per topic %s.

What it means

internalUpdatePartitionedTopicAsync pre-check failure (422): the requested partition count exceeds the cluster's maximum allowed partitions per topic, so the update is rejected to prevent creating more partitions than the broker configuration permits.

Solutions

1. Request a count within maxPartitionsPerTopic
2. Ask the admin to raise maxPartitionsPerTopic if a larger topic is genuinely needed

When it happens

Trigger: Thrown at pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/PersistentTopicsBase.java:394 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/221bfa914c0f108d. Report an issue: GitHub.

Appendix: source

Thrown at pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/PersistentTopicsBase.java:394

                                                                                   boolean updateLocal,
                                                                                   boolean force) {
        PulsarService pulsarService = pulsar();
        return pulsarService.getBrokerService().fetchPartitionedTopicMetadataAsync(topicName)
            .thenCompose(partitionedTopicMetadata -> {
                int currentMetadataPartitions = partitionedTopicMetadata.partitions;
                if (currentMetadataPartitions <= 0) {
                    throw new RestException(Status.CONFLICT /* Unprocessable entity*/,
                            String.format("Topic %s is not the partitioned topic.", topicName));
                }
                if (expectPartitions < currentMetadataPartitions) {
                    throw new RestException(422 /* Unprocessable entity*/,
                            String.format("Desired partitions %s can't be less than the current partitions %s.",
                                    expectPartitions, currentMetadataPartitions));
                }
                int brokerMaximumPartitionsPerTopic = pulsarService.getConfiguration()
                        .getMaxNumPartitionsPerPartitionedTopic();
                if (brokerMaximumPartitionsPerTopic > 0 && expectPartitions > brokerMaximumPartitionsPerTopic) {
                    throw new RestException(422 /* Unprocessable entity*/,
                            String.format("Desired partitions %s can't be greater than the maximum partitions per"
                                            + " topic %s.",
                                    expectPartitions, brokerMaximumPartitionsPerTopic));
                }
                final PulsarAdmin admin;
                try {
                    admin = pulsarService.getAdminClient();
                } catch (PulsarServerException ex) {
                    throw new RestException(Status.INTERNAL_SERVER_ERROR, Throwables.getRootCause(ex));
                }
                final CompletableFuture<Void> checkFuture;
                if (!force) {
                    checkFuture = admin.topics().getListAsync(topicName.getNamespace(), topicName.getDomain())
                            .thenAccept(topics -> {
                                final List<TopicName> existingPartitions = topics.stream()
                                        .map(TopicName::get)
                                        .filter(candidateTopicName -> candidateTopicName.getPartitionedTopicName()
                                                .equals(topicName.getPartitionedTopicName()))

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