n8n-io/n8n · error · UnexpectedError

Invalid file_ids type

Error message

Invalid file_ids type

What it means

The getFileIds helper in the Update Assistant operation parses the file_ids parameter into an array. It accepts either an array (passed directly) or a comma-separated string (split and trimmed). Any other type (number, object, boolean, null that is not caught earlier) throws an UnexpectedError — indicating a programming/config bug rather than a user input error, since the node parameter type should constrain input to string or fixedCollection array.

Source

Thrown at packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/v1/actions/assistant/update.operation.ts:129

const displayOptions = {
	show: {
		operation: ['update'],
		resource: ['assistant'],
	},
};

export const description = updateDisplayOptions(displayOptions, properties);

function getFileIds(file_ids: unknown): string[] {
	if (Array.isArray(file_ids)) {
		return file_ids;
	}

	if (typeof file_ids === 'string') {
		return file_ids.split(',').map((file_id) => file_id.trim());
	}

	throw new UnexpectedError('Invalid file_ids type');
}

export async function execute(this: IExecuteFunctions, i: number): Promise<INodeExecutionData[]> {
	const assistantId = this.getNodeParameter('assistantId', i, '', { extractValue: true }) as string;
	const options = this.getNodeParameter('options', i, {});

	const {
		modelId,
		name,
		instructions,
		codeInterpreter,
		knowledgeRetrieval,
		file_ids,
		removeCustomTools,
		temperature,
		topP,
	} = options;

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Set file_ids as a comma-separated string (e.g. 'file-abc,file-def') or as a fixedCollection array in the node UI
2. If importing the workflow from JSON, ensure file_ids is a string or array, not a number or object
3. If this appears during normal UI usage, report it as a node definition bug

Example fix

// before — file_ids: { id: 'file-abc' } (object)
// after  — file_ids: 'file-abc' (string)

function validateFileIds(value: unknown): string[] {
  if (Array.isArray(value)) return value as string[];
  if (typeof value === 'string') return value.split(',').map(s => s.trim());
  throw new UserError('file_ids must be an array or comma-separated string');
}

function isFileIdsInput(value: unknown): value is string | string[] {
  return typeof value === 'string' || (Array.isArray(value) && value.every(v => typeof v === 'string'));
}

When it happens

Trigger: The file_ids parameter in the Update Assistant options is populated with a value that is neither an array nor a string. This typically requires the node parameter value to be set programmatically or via API in a way that bypasses the UI type constraints.

Common situations: Workflow imported from JSON where file_ids was set to a number or object; programmatic workflow construction via the n8n API that doesn't match the expected parameter type; a node definition change that altered the parameter type without updating getFileIds.

Related errors

• An assistant with the same name '${name}' already exists
• The maximum number of files that can be attached to the assi
• ${error.message}
• The maximum number of files that can be attached to the assi
• The file content is not in JSONL format

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/57884f845a66bdbd. Report an issue: GitHub.