mem0ai/mem0 · error · NodeOperationError

Invalid JSON in "Metadata" field

Error message

Invalid JSON in "Metadata" field

What it means

A 400 raised by _validate_bundled_providers when the submitted config specifies an LLM provider (config['llm']['provider']) that is not in BUNDLED_LLM_PROVIDERS for this server image. The Docker image only ships the Python packages for a fixed list of providers; requesting any other provider cannot work at runtime, so the server rejects the config up front with instructions to extend the image.

Source

Thrown at integrations/n8n-nodes-mem0/nodes/Mem0/Mem0.node.ts:426

					}
					const addFields = this.getNodeParameter('addFields', i, {}) as IDataObject;
					const body: IDataObject = {
						messages: messagesUi.map((m) => ({ role: m.role, content: m.content })),
						infer: addFields.infer !== undefined ? addFields.infer : true,
					};
					const userId = this.getNodeParameter('userId', i, '') as string;
					if (userId) body.user_id = userId;
					if (addFields.agent_id) body.agent_id = addFields.agent_id;
					if (addFields.app_id) body.app_id = addFields.app_id;
					if (addFields.run_id) body.run_id = addFields.run_id;
					if (addFields.metadata) {
						try {
							body.metadata =
								typeof addFields.metadata === 'string'
									? JSON.parse(addFields.metadata as string)
									: addFields.metadata;
						} catch {
							throw new NodeOperationError(this.getNode(), 'Invalid JSON in "Metadata" field', {
								itemIndex: i,
							});
						}
					}

					// Custom extraction controls (optional): steer what the API extracts.
					if (addFields.custom_instructions) {
						body.custom_instructions = addFields.custom_instructions;
					}
					if (addFields.custom_categories) {
						try {
							body.custom_categories =
								typeof addFields.custom_categories === 'string'
									? JSON.parse(addFields.custom_categories as string)
									: addFields.custom_categories;
						} catch {
							throw new NodeOperationError(
								this.getNode(),

View on GitHub (pinned to 001c235229)

Solutions

1. Check the bundled list in the error message and switch config['llm']['provider'] to one of those (e.g. 'openai').
2. Or build a custom image: pip install the provider's package in the Dockerfile and extend BUNDLED_LLM_PROVIDERS in server/main.py, then rebuild.
3. Or run the server from source (pip install mem0ai[<provider>] plus the server package) instead of the prebuilt image.
4. Verify the provider string matches exactly (lowercase, no extra spaces) what mem0 expects.

Example fix

# before
{"llm": {"provider": "anthropic", "config": {"model": "claude-3-5-sonnet"}}}

# after (image bundles openai)
{"llm": {"provider": "openai", "config": {"model": "gpt-4o-mini", "api_key": "..."}}}

BUNDLED_LLM_PROVIDERS = {"openai", "azure_openai", "anthropic", "gemini"}  # mirror the image's list

def validate_llm_config(cfg: dict) -> None:
    llm = cfg.get("llm") or {}
    provider = llm.get("provider", "openai")
    if provider not in BUNDLED_LLM_PROVIDERS:
        raise ValueError(f"LLM provider '{provider}' not bundled; pick from {sorted(BUNDLED_LLM_PROVIDERS)}")

def is_bundled_llm(provider: str, bundled: set[str]) -> bool:
    return provider in bundled

if resp.status_code == 400 and "not bundled" in resp.text:
    raise ConfigError(resp.json()["detail"])  # config error, not transient: do not retry

When it happens

Trigger: POST/PUT of a config with e.g. "llm": {"provider": "anthropic"} when 'anthropic' is not in the image's BUNDLED_LLM_PROVIDERS; migrating a config from a pip-installed deployment (which could install any provider) to the prebuilt Docker image; a typo in the provider name.

Common situations: Self-hosting the official container and wanting a provider the image does not bundle; a new provider exists in mem0ai on PyPI but the Docker image predates it; copying an example config that uses a niche provider.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Invalid JSON in "Custom Categories" field
• Resource not found: ${path}
• At least one message is required
• Add requires at least one of User ID, Agent ID, Run ID, or A
• Provide at least one of User ID, Agent ID, App ID, or Run ID

AI-assisted analysis of mem0ai/mem0@001c235229 (2026-08-15). Data as JSON: /api/errors/0ba09c2e963279d6. Report an issue: GitHub.