apache/pulsar · error · IllegalArgumentException

Input Topics cannot be altered

Error message

Input Topics cannot be altered

What it means

Thrown by SinkConfigUtils.validateUpdate when the new config's inputSpecs contains a topic that is not present in the existing config's inputSpecs. Input topics of a deployed sink cannot be added or changed via update; only their ConsumerConfig values are merged for already-known topics.

Source

Thrown at pulsar-functions/utils/src/main/java/org/apache/pulsar/functions/utils/SinkConfigUtils.java:674

                                .serdeClassName(serdeClassName)
                                .isRegexPattern(false)
                                .build());
            });
        }
        if (newConfig.getTopicToSchemaType() != null) {
            newConfig.getTopicToSchemaType().forEach((topicName, schemaClassname) -> {
                newConfig.getInputSpecs().put(topicName,
                        ConsumerConfig.builder()
                                .schemaType(schemaClassname)
                                .isRegexPattern(false)
                                .build());
            });
        }
        if (!newConfig.getInputSpecs().isEmpty()) {
            SinkConfig finalMergedConfig = mergedConfig;
            newConfig.getInputSpecs().forEach((topicName, consumerConfig) -> {
                if (!existingConfig.getInputSpecs().containsKey(topicName)) {
                    throw new IllegalArgumentException("Input Topics cannot be altered");
                }
                if (consumerConfig.isRegexPattern() != existingConfig.getInputSpecs().get(topicName).isRegexPattern()) {
                    throw new IllegalArgumentException(
                            "isRegexPattern for input topic " + topicName + " cannot be altered");
                }
                finalMergedConfig.getInputSpecs().put(topicName, consumerConfig);
            });
        }
        if (newConfig.getProcessingGuarantees() != null && !newConfig.getProcessingGuarantees()
                .equals(existingConfig.getProcessingGuarantees())) {
            throw new IllegalArgumentException("Processing Guarantees cannot be altered");
        }
        if (newConfig.getConfigs() != null) {
            mergedConfig.setConfigs(newConfig.getConfigs());
        }
        if (newConfig.getSecrets() != null) {
            mergedConfig.setSecrets(newConfig.getSecrets());
        }

View on GitHub (pinned to 820761864e)

Solutions

1. Ensure inputSpecs in the update contains exactly the same topic keys as the existing sink
2. To change input topics, delete the sink and create a new one with the desired topic set
3. Diff the inputSpecs of the update payload against 'pulsar-admin sinks get' output before updating

Example fix

// before
sinkConfig.setInputSpecs(Map.of("persistent://public/default/new-topic", new ConsumerConfig()));
admin.sinks().updateSink(tenant, namespace, sinkConfig, null);
// after
sinkConfig.setInputSpecs(existingInputSpecs); // same topic keys as deployed sink
admin.sinks().updateSink(tenant, namespace, sinkConfig, null);

Set<String> existingTopics = existing.getInputSpecs().keySet();
Set<String> newTopics = newCfg.getInputSpecs() == null ? Set.of() : newCfg.getInputSpecs().keySet();
if (!existingTopics.containsAll(newTopics)) {
    throw new IllegalArgumentException("Input topics are immutable; found new topics: " + newTopics);
}

try {
    admin.sinks().updateSink(tenant, namespace, cfg, null);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("Input Topics cannot be altered")) { /* restore original inputSpecs */ }
    else throw e;
}

When it happens

Trigger: Updating a sink with an inputSpecs map containing a topic name absent from the deployed config (added topic), or a renamed topic key.

Common situations: Developer adds a new input topic to the YAML and runs update instead of recreating; topic renamed after a refactor; config generated from scratch omits the original topic list.

Related errors

• Sink Names differ
• Subscription Name cannot be altered
• isRegexPattern for input topic cannot be altered
• Processing Guarantees cannot be altered
• Retain Ordering cannot be altered

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/63f8fd8aabf426ff. Report an issue: GitHub.