n8n-io/n8n · error · UserError

Invalid payload type

Error message

Invalid payload type

What it means

Thrown as a UserError by the In-Memory vector store's `createVectorStore` action handler when the `payload` argument is missing (`undefined`) or a plain string rather than an `IDataObject`. The action handler is invoked from the editor UI to materialize a named in-memory store; it expects an object carrying at least a `name` field.

Source

Thrown at packages/@n8n/nodes-langchain/nodes/vector_store/VectorStoreInMemory/VectorStoreInMemory.node.ts:166

					});

				let results = searchOptions;
				if (filter) {
					results = results.filter((option) => option.name.includes(filter));
				}

				return {
					results,
				};
			},
		},
		actionHandler: {
			async createVectorStore(
				this: ILoadOptionsFunctions,
				payload: string | IDataObject | undefined,
			): Promise<NodeParameterValueType> {
				if (!payload || typeof payload === 'string') {
					throw new UserError('Invalid payload type');
				}

				const { name } = payload;

				const vectorStoreSingleton = MemoryVectorStoreManager.getInstance(
					{} as Embeddings, // Real Embeddings are provided when executing the node
					this.logger,
				);

				const memoryKey = name ? (name as string) : DEFAULT_MEMORY_KEY;
				await vectorStoreSingleton.getVectorStore(memoryKey);

				return memoryKey;
			},
		},
	},
	insertFields,
	loadFields: [warningBanner],

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Ensure the action handler is invoked with an `IDataObject` payload (e.g. `{ name: 'myStore' }`).
2. If a string is genuinely desired, wrap it before calling: `{ name: theString }`.
3. Update the caller (editor-ui or test) to the current action payload contract.

Example fix

// before
if (!payload || typeof payload === 'string') {
  throw new UserError('Invalid payload type');
}

// after: accept a string by coercing it into the expected shape
const source = typeof payload === 'string' ? { name: payload } : payload;
if (!source || typeof source !== 'object') {
  throw new UserError('Invalid payload type: expected an object or a string');
}
const { name } = source as IDataObject;

// Normalize the payload before validating so callers can pass either shape.
function normalizePayload(payload: string | IDataObject | undefined): IDataObject {
  if (typeof payload === 'string') return { name: payload };
  if (payload && typeof payload === 'object') return payload;
  throw new UserError('Invalid payload type');
}

function isActionPayload(value: unknown): value is IDataObject {
  return typeof value === 'object' && value !== null && !Array.isArray(value);
}

// No try/catch needed; this is a synchronous type guard.
if (!isActionPayload(payload)) {
  throw new UserError('Invalid payload type');
}

When it happens

Trigger: The UI invokes the action handler with a string (older action payload shape), or with `undefined` because the user submitted the form without the action payload; programmatic invocation of the action handler with a malformed argument.

Common situations: Custom UI or another node calling the action handler with the wrong payload type; downgrade/upgrade of editor-ui that changed the action payload contract; test harness invoking the handler without an object.

Related errors

• Collection must be a string
• Parameter ${key} must be a string
• Error: No JSON string provided.
• Invalid Qdrant URL: ${url}. Please provide a valid URL with
• Failed to initialize Chroma collection

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/a987eef8ee4b4cc3. Report an issue: GitHub.