apache/pulsar · error · RestException

maxSubscriptionsPerTopic must be 0 or more

Error message

maxSubscriptionsPerTopic must be 0 or more

What it means

Raised by internalSetMaxSubscriptionsPerTopic when the supplied maxSubscriptionsPerTopic value is negative; the namespace-policy write is rejected with 412 Precondition Failed before any policy update because the limit must be zero (unlimited) or a positive integer.

Source

Thrown at pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/NamespacesBase.java:2572

                    .attr("maxUnackedMessagesPerConsumer", maxUnackedMessagesPerConsumer)
                    .log("Successfully updated maxUnackedMessagesPerConsumer configuration");

        } catch (RestException pfe) {
            throw pfe;
        } catch (Exception e) {
            log.error()
                    .attr("namespace", namespaceName)
                    .exception(e)
                    .log("Failed to update maxUnackedMessagesPerConsumer configuration");
            throw new RestException(e);
        }
    }

    protected void internalSetMaxSubscriptionsPerTopic(Integer maxSubscriptionsPerTopic){
        validateNamespacePolicyOperation(namespaceName, PolicyName.MAX_SUBSCRIPTIONS, PolicyOperation.WRITE);
        validatePoliciesReadOnlyAccess();
        if (maxSubscriptionsPerTopic != null && maxSubscriptionsPerTopic < 0) {
            throw new RestException(Status.PRECONDITION_FAILED,
                    "maxSubscriptionsPerTopic must be 0 or more");
        }
        internalSetPolicies("max_subscriptions_per_topic", maxSubscriptionsPerTopic);
    }

    protected void internalSetMaxUnackedMessagesPerSubscription(Integer maxUnackedMessagesPerSubscription) {
        validateNamespacePolicyOperation(namespaceName, PolicyName.MAX_UNACKED, PolicyOperation.WRITE);
        validatePoliciesReadOnlyAccess();
        if (maxUnackedMessagesPerSubscription != null && maxUnackedMessagesPerSubscription < 0) {
            throw new RestException(Status.PRECONDITION_FAILED,
                    "maxUnackedMessagesPerSubscription must be 0 or more");
        }
        try {
            updatePolicies(namespaceName, policies -> {
                policies.max_unacked_messages_per_subscription = maxUnackedMessagesPerSubscription;
                return policies;
            });
            log.info()

View on GitHub (pinned to 820761864e)

Solutions

1. Supply 0 (unlimited) or a positive subscription count
2. Omit the field to leave the policy unchanged

When it happens

Trigger: Thrown at pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/NamespacesBase.java:2572 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/61042d5a46e96222. Report an issue: GitHub.