INVALID_DATE_METHOD

INVALID_DATE_METHOD

Error message

'${node.name}' parameter "${path}" uses .toISOString() which is a JS Date method. Use .toISO() for Luxon DateTime ($now, $today).

What it means

Warning-level validator issue (code INVALID_DATE_METHOD) emitted when a parameter value string contains '.toISOString()', which is a JavaScript Date method. n8n's $now and $today are Luxon DateTime objects, whose equivalent method is .toISO(). Using the JS method will fail at evaluation time, so the validator flags it preemptively.

Source

Thrown at packages/@n8n/workflow-sdk/src/workflow-builder/plugins/validators/date-method-validator.ts:38

	priority: 30,

	validateNode(
		node: NodeInstance<string, string, unknown>,
		_graphNode: GraphNode,
		_ctx: PluginContext,
	): ValidationIssue[] {
		const issues: ValidationIssue[] = [];

		const params = node.config?.parameters;
		if (!params) {
			return issues;
		}

		const dateIssues = findInvalidDateMethods(params);

		for (const { path } of dateIssues) {
			issues.push({
				code: 'INVALID_DATE_METHOD',
				message: `'${node.name}' parameter "${path}" uses .toISOString() which is a JS Date method. Use .toISO() for Luxon DateTime ($now, $today).`,
				severity: 'warning',
				nodeName: node.name,
				parameterPath: path,
			});
		}

		return issues;
	},
};

View on GitHub (pinned to 5ac6606e81)

Solutions

Replace .toISOString() with .toISO() for any Luxon DateTime ($now, $today).
Verify the result format matches expectations (ISO string).
Re-run validation to confirm the issue clears.

Example fix

// before
'={{ $now.toISOString() }}'
// after
'={{ $now.toISO() }}'

Defensive patterns

Strategy: validation

Validate before calling

/\.toISOString\(\)/.test(String(paramValue))
  // warn: Luxon DateTime ($now/$today) should use .toISO()

Prevention

Remember $now and $today are Luxon DateTime, not JS Date.
Use .toISO() for ISO strings, .toMillis() for epoch, .plus()/.minus() for arithmetic.
Search expressions for '.toISOString' before exporting.

When it happens

Trigger: Writing an expression like '={{ $now.toISOString() }}' or '={{ $today.toISOString() }}' in any node parameter.

Common situations: Copying JS Date code into an expression; LLM-generated workflow that assumes native Date; muscle memory from non-Luxon environments.

Related errors

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/9090dc1ab23b288b. Report an issue: GitHub.