alibaba/nacos · error · IllegalArgumentException

AgentVersionContent JSON must not be empty

Error message

AgentVersionContent JSON must not be empty

What it means

Thrown by validateSingleJsonValue when the JSON parser yields no tokens at all — the byte array is empty or contains only whitespace/comments that produce zero JSON tokens. Persisted content must be a non-empty JSON value.

Source

Thrown at ai/src/main/java/com/alibaba/nacos/ai/service/agent/storage/AgentVersionContentSerializer.java:274

            Map<?, ?> interfaceObject = (Map<?, ?>) callInterface;
            rejectUnknownFields(interfaceObject, CALL_INTERFACE_FIELDS, "AgentCallInterface");
            Object endpoints = interfaceObject.get("declaredEndpoints");
            if (!(endpoints instanceof List)) {
                continue;
            }
            for (Object endpoint : (List<?>) endpoints) {
                if (endpoint instanceof Map) {
                    rejectUnknownFields((Map<?, ?>) endpoint, ENDPOINT_FIELDS,
                        "DeclaredEndpoint");
                }
            }
        }
    }
    
    private static void validateSingleJsonValue(byte[] bytes) {
        try (JsonParser parser = STRICT_JSON_FACTORY.createParser(bytes)) {
            if (parser.nextToken() == null) {
                throw new IllegalArgumentException("AgentVersionContent JSON must not be empty");
            }
            parser.skipChildren();
            if (parser.nextToken() != null) {
                throw new IllegalArgumentException(
                    "AgentVersionContent must contain one JSON value");
            }
        } catch (IOException e) {
            throw new IllegalArgumentException("Invalid AgentVersionContent", e);
        }
    }
    
    private static void rejectUnknownFields(Map<?, ?> value, Set<String> fields,
        String objectName) {
        for (Object field : value.keySet()) {
            if (!fields.contains(field)) {
                throw new IllegalArgumentException("Unknown " + objectName + " field: " + field);
            }
        }

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Ensure content is always serialized through serialize() which produces non-empty JSON.
2. Restore or re-publish the version if the stored bytes are empty.
3. Guard empty bytes before calling deserialize.

if (bytes == null || bytes.length == 0) {
    throw new NacosException(NacosException.SERVER_ERROR, "empty content bytes");
}

When it happens

Trigger: Deserializing a zero-length byte array, or bytes containing only whitespace. The strict Jackson parser's first nextToken() returns null.

Common situations: A storage cell was written empty, or a truncation left zero bytes. Also in tests passing new byte[0].

Related errors

• AgentVersionContent must be a JSON object
• AgentVersionContent must contain one JSON value
• Invalid AgentVersionContent
• Unknown {objectName} field: {field}
• 20002

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/8eaf0df9bf17ef13. Report an issue: GitHub.