alibaba/nacos · error · IllegalArgumentException

{fieldName} must not be JSON null

Error message

{fieldName} must not be JSON null

What it means

Error "{fieldName} must not be JSON null" thrown in alibaba/nacos.

Source

Thrown at api/src/main/java/com/alibaba/nacos/api/ai/utils/AgentValidationUtils.java:226

     * @throws IllegalArgumentException when invalid
     */
    public static void validateMediaType(String mediaType) {
        if (mediaType == null || mediaType.length() > MAX_MEDIA_TYPE_LENGTH
            || !MEDIA_TYPE_PATTERN.matcher(mediaType).matches()) {
            throw new IllegalArgumentException("Invalid descriptorMediaType: " + mediaType);
        }
    }
    
    /**
     * Validate a required JSON-compatible value after request binding.
     *
     * @param value JSON-compatible value
     * @param fieldName field name used in validation errors
     * @throws IllegalArgumentException when the value is {@code null}
     */
    public static void validateNonNullJsonValue(Object value, String fieldName) {
        if (value == null) {
            throw new IllegalArgumentException(fieldName + " must not be JSON null");
        }
    }
    
    /**
     * Validate optional public Endpoint metadata.
     *
     * @param metadata Endpoint metadata, or {@code null}
     * @throws IllegalArgumentException when invalid or using a reserved key
     */
    public static void validateEndpointMetadata(Map<String, String> metadata) {
        if (metadata == null) {
            return;
        }
        if (metadata.size() > MAX_METADATA_SIZE) {
            throw new IllegalArgumentException(
                "Endpoint metadata exceeds " + MAX_METADATA_SIZE + " entries");
        }
        for (Map.Entry<String, String> entry : metadata.entrySet()) {

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Review the input and runtime state for JSON null field, correct the reported problem, and retry.

When it happens

Trigger: Thrown at api/src/main/java/com/alibaba/nacos/api/ai/utils/AgentValidationUtils.java:226 when the library encounters an invalid state.

Common situations: A field was explicitly set to JSON null where a real value is required.

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/1af30846f11517a8. Report an issue: GitHub.