n8n-io/n8n · error · NodeOperationError

Invalid document at index

Error message

Invalid document at index ${invalidIndex}

What it means

Generic input-validation error from validateEmbedDocumentsInput, wrapped as NodeOperationError with the node for context. It fires when a document entry in the documents array is undefined, null, or an empty string — an unusable item for embedding. The array itself was valid; one indexed item was not.

Solutions

1. Ensure every element of the documents array is a non-empty string before calling validateEmbedDocumentsInput.
2. Filter out null, undefined, and empty-string entries upstream, or fix the upstream node so it emits valid text for each item.
3. Check the input data mapping: a missing field or empty expression result commonly produces null/empty entries at some index.

When it happens

Trigger: Thrown at packages/@n8n/ai-utilities/src/utils/embeddings-input-validation.ts:44 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/b7b9458ef321011d. Report an issue: GitHub.

Appendix: source

Thrown at packages/@n8n/ai-utilities/src/utils/embeddings-input-validation.ts:44

 *
 * @param documents - The documents array to validate
 * @param node - The node for error context
 * @returns The validated documents array
 * @throws NodeOperationError if documents is not an array or contains invalid entries
 */
export function validateEmbedDocumentsInput(documents: unknown, node: INode): string[] {
	if (!Array.isArray(documents)) {
		throw new NodeOperationError(node, 'Documents must be an array', {
			description: 'Expected an array of strings to embed.',
		});
	}

	const invalidIndex = documents.findIndex(
		(doc) => doc === undefined || doc === null || doc === '',
	);

	if (invalidIndex !== -1) {
		throw new NodeOperationError(node, `Invalid document at index ${invalidIndex}`, {
			description: `Document at index ${invalidIndex} is empty or undefined. All documents must be non-empty strings.`,
		});
	}

	return documents;
}

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