requested(${__.name}, ${limit}) cannot be used with synchron

Error message

requested(${__.name}, ${limit}) cannot be used with synchronous iteration because the query validator is async. Use `for await ... of` instead

What it means

requested() with a numeric limit supports iteration over tracked query payloads. If the query's validator returns a promise (is thenable), synchronous for...of cannot consume it, so this error directs you to async iteration.

Source

Thrown at packages/kit/src/runtime/app/server/remote/requested.js:174

		const promise = Promise.reject(error);
		promise.catch(noop);

		get_cache(__, state)[payload] = promise;
		refresh(event, state, __, payload, () => promise);
	};

	for (const payload of skipped) consume(payload);

	const result = {
		*[Symbol.iterator]() {
			for (const payload of selected) {
				consume(payload);
				try {
					const parsed = parse_remote_arg(payload);
					const validated = __.validate(parsed);

					if (is_thenable(validated)) {
						throw new Error(
							// TODO improve
							`requested(${__.name}, ${limit}) cannot be used with synchronous iteration because the query validator is async. Use \`for await ... of\` instead`
						);
					}

					yield {
						arg: validated,
						query: __.bind(payload, validated),
						ignore: create_ignore(payload)
					};
				} catch (error) {
					record_failure(payload, error);
					continue;
				}
			}
		},
		async *[Symbol.asyncIterator]() {
			yield* race_all(selected, async (payload) => {

View on GitHub (pinned to 03f1687fe6)

Solutions

Use for await (const item of requested(q, limit)) instead of for...of
Make the query validator synchronous so sync iteration works
Pre-validate the payload synchronously and keep validate non-async

Example fix

// before
for (const item of requested(getPosts, 5)) { /* throws */ }
// after
for await (const item of requested(getPosts, 5)) { /* ok */ }

Defensive patterns

Strategy: try-catch

Validate before calling

null

Type guard

null

Try / catch

try {
  for await (const item of requested(q, limit)) {
    consume(item);
  }
} catch (e) {
  // handle per-item errors during async iteration
}

Prevention

Prefer for await...of when iterating requested(...) with a limit
Keep query validators synchronous if sync iteration is needed
Audit async schema validators in query definitions

When it happens

Trigger: Iterating requested(query, limit) with for...of when the query's validate function is async or returns a Promise (e.g. schema validators returning promises, async Zod refinements).

Common situations: Using async validation libraries (Zod async schemas, class-validator) in the query; switching a validator from sync to async after adding requested() iteration.

Related errors

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/b7e22755c7724930. Report an issue: GitHub.