alibaba/nacos · error · IllegalArgumentException

Agent Version mediaType must be {AGENT_VERSION_MEDIA_TYPE}

Error message

Agent Version mediaType must be {AGENT_VERSION_MEDIA_TYPE}

What it means

The mediaType field must equal exactly 'application/vnd.nacos.agent-version+json' (AgentVersionStorageDescriptor.MEDIA_TYPE). Any other value, including null or generic 'application/json', is rejected. The media type pins the descriptor payload format.

Source

Thrown at ai/src/main/java/com/alibaba/nacos/ai/service/agent/storage/AgentVersionStorageDescriptorSerializer.java:169

     */
    public static void validate(AgentVersionStorageDescriptor descriptor) {
        if (descriptor == null) {
            throw new IllegalArgumentException("Agent Version storage descriptor must not be null");
        }
        String provider = descriptor.getProvider();
        if (provider == null || provider.length() > MAX_PROVIDER_LENGTH
            || !PROVIDER_PATTERN.matcher(provider).matches()) {
            throw new IllegalArgumentException("Invalid Agent Version storage provider");
        }
        validateRequiredText("key", descriptor.getKey(), MAX_KEY_LENGTH);
        validateOptionalText("keyFormat", descriptor.getKeyFormat(), MAX_FORMAT_LENGTH);
        validateOptionalText("agentNameCodec", descriptor.getAgentNameCodec(), MAX_FORMAT_LENGTH);
        if (descriptor.getContentDigest() == null
            || !DIGEST_PATTERN.matcher(descriptor.getContentDigest()).matches()) {
            throw new IllegalArgumentException("Invalid Agent Version contentDigest");
        }
        if (!AGENT_VERSION_MEDIA_TYPE.equals(descriptor.getMediaType())) {
            throw new IllegalArgumentException("Agent Version mediaType must be "
                + AGENT_VERSION_MEDIA_TYPE);
        }
        if (!Integer.valueOf(SCHEMA_VERSION).equals(descriptor.getSchemaVersion())) {
            throw new IllegalArgumentException("Agent Version storage schemaVersion must be "
                + SCHEMA_VERSION);
        }
        Long size = descriptor.getSize();
        if (size == null || size < 0 || size > MAX_CONTENT_SIZE) {
            throw new IllegalArgumentException(
                "Agent Version storage size must be between 0 and " + MAX_CONTENT_SIZE);
        }
        if (NACOS_CONFIG_PROVIDER.equals(provider)) {
            if (!NACOS_CONFIG_KEY_FORMAT.equals(descriptor.getKeyFormat())) {
                throw new IllegalArgumentException("nacos_config keyFormat must be "
                    + NACOS_CONFIG_KEY_FORMAT);
            }
            if (!RAD_ASCII_AGENT_NAME_CODEC.equals(descriptor.getAgentNameCodec())) {
                throw new IllegalArgumentException("nacos_config agentNameCodec must be "

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Set mediaType to AgentVersionStorageDescriptor.MEDIA_TYPE
2. Use AgentVersionStorageService.buildDescriptor/buildReplacementDescriptor, which set it correctly
3. Re-publish the version to regenerate the descriptor

Example fix

// before
descriptor.setMediaType("application/json");
// after
descriptor.setMediaType(AgentVersionStorageDescriptor.MEDIA_TYPE);

if (!AgentVersionStorageDescriptor.MEDIA_TYPE.equals(descriptor.getMediaType())) {
    descriptor.setMediaType(AgentVersionStorageDescriptor.MEDIA_TYPE);
}

When it happens

Trigger: validate()/serialize() on a descriptor whose mediaType is null, "application/json", or any other string. Fires on a stale/corrupted row too.

Common situations: Hardcoding 'application/json'; leaving mediaType unset; a descriptor from an older Nacos version that used a different media type.

Related errors

• Agent Version storage descriptor JSON must not be empty
• Agent Version storage descriptor must be a JSON object
• Unknown Agent Version storage descriptor field: {fieldName}
• Agent Version storage descriptor must not be null
• Invalid Agent Version storage provider

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/cfadc0cea3ef21bd. Report an issue: GitHub.