alibaba/nacos · error · IllegalArgumentException

AgentVersionContent kind must be {AgentVersionContent.KIND}

Error message

AgentVersionContent kind must be {AgentVersionContent.KIND}

What it means

Thrown by validate when content.getKind() does not equal the constant AgentVersionContent.KIND ("AgentVersionContent"). The kind field is a discriminator ensuring persisted content is self-identifying and resistant to schema confusion.

Source

Thrown at ai/src/main/java/com/alibaba/nacos/ai/service/agent/storage/AgentVersionContentSerializer.java:147

                "AgentVersionContent exceeds " + MAX_CONTENT_SIZE + " bytes");
        }
        validateStorageJsonShape(bytes);
        final AgentVersionContent content;
        try {
            content = JacksonUtils.toObj(bytes, AgentVersionContent.class);
        } catch (NacosDeserializationException e) {
            throw new IllegalArgumentException("Invalid AgentVersionContent", e);
        }
        validate(content);
        return content;
    }
    
    private static void validate(AgentVersionContent content) {
        if (content == null) {
            throw new IllegalArgumentException("AgentVersionContent must not be null");
        }
        if (!AgentVersionContent.KIND.equals(content.getKind())) {
            throw new IllegalArgumentException("AgentVersionContent kind must be "
                + AgentVersionContent.KIND);
        }
        if (!Integer.valueOf(AgentVersionContent.SCHEMA_VERSION)
            .equals(content.getSchemaVersion())) {
            throw new IllegalArgumentException("AgentVersionContent schemaVersion must be "
                + AgentVersionContent.SCHEMA_VERSION);
        }
        List<AgentCallInterface> callInterfaces = content.getCallInterfaces();
        if (callInterfaces == null || callInterfaces.isEmpty()
            || callInterfaces.size() > MAX_CALL_INTERFACES) {
            throw new IllegalArgumentException(
                "AgentVersionContent callInterfaces must contain 1 to " + MAX_CALL_INTERFACES
                    + " items");
        }
        Set<String> protocols = new HashSet<String>();
        for (AgentCallInterface callInterface : callInterfaces) {
            AgentModelValidator.validateCallInterface(callInterface);
            if (!protocols.add(callInterface.getProtocol())) {

View on GitHub (pinned to 9b989acdf1)

Solutions

Use new AgentVersionContent(callInterfaces) which sets kind and schemaVersion automatically.
If setting fields manually, call content.setKind(AgentVersionContent.KIND).
Ensure the JSON you deserialize was produced by this serializer's serialize method.

Example fix

// before
AgentVersionContent c = new AgentVersionContent();
c.setCallInterfaces(ifaces);

// after
AgentVersionContent c = new AgentVersionContent(ifaces); // sets kind + schemaVersion

Defensive patterns

Strategy: validation

Validate before calling

AgentVersionContent c = new AgentVersionContent(callInterfaces); // sets kind automatically
// or manually:
c.setKind(AgentVersionContent.KIND);

Prevention

Use the parameterized constructor which sets kind and schemaVersion.
Avoid the default constructor unless you set all discriminator fields.

When it happens

Trigger: Serializing or deserializing content whose kind field is missing, null, or set to a different string. This happens when content is built manually without setting kind, or when a JSON document from a different schema is loaded.

Common situations: Manually constructing AgentVersionContent without using the constructor that sets kind (the default constructor leaves kind null), or loading a JSON blob intended for a different resource type.

Related errors

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/34f70179429606dd. Report an issue: GitHub.