alibaba/spring-ai-alibaba · error · IllegalStateException

no more elements into iterator

Error message

no more elements into iterator

What it means

This iterator wraps fetched Data<E> in an AtomicReference (currentFetchedData). next() throws IllegalStateException when the previously fetched element is null or done, meaning the caller iterated past the end of the underlying delegate iterator.

Source

Thrown at spring-ai-alibaba-graph-core/src/main/java/com/alibaba/cloud/ai/graph/async/AsyncGenerator.java:476

	final AtomicReference<AsyncGenerator.Data<E>> currentFetchedData;

	public InternalIterator(AsyncGenerator<E> delegate) {
		this.delegate = delegate;
		currentFetchedData = new AtomicReference<>(delegate.next());
	}

	@Override
	public boolean hasNext() {
		final var value = currentFetchedData.get();
		return value != null && !value.isDone();
	}

	@Override
	public E next() {
		var next = currentFetchedData.get();

		if (next == null || next.isDone()) {
			throw new IllegalStateException("no more elements into iterator");
		}

		if (!next.isError()) {
			currentFetchedData.set(delegate.next());
		}

		return next.data.join();
	}

	@Override
	public Optional<Object> resultValue() {
		if (delegate instanceof AsyncGenerator.HasResultValue withResult) {
			return withResult.resultValue();
		}
		return Optional.empty();
	}

};

View on GitHub (pinned to f82da0b50f)

Solutions

1. Always guard with hasNext() before calling next()
2. Stop iterating as soon as Data.isDone() is true
3. Use for-each or stream APIs over the AsyncGenerator instead of manual next() calls
4. If resuming iteration across async boundaries, re-check completion state before next()

Example fix

// before
while (true) { E e = iterator.next(); ... } // throws at end
// after
while (iterator.hasNext()) { E e = iterator.next(); ... }

if (currentFetchedData == null || currentFetchedData.isDone()) return; // end of iteration

static <E> boolean hasRemaining(java.util.Iterator<E> it) { return it.hasNext(); }

try { E e = it.next(); } catch (IllegalStateException e) { if ("no more elements into iterator".equals(e.getMessage())) { /* treat as end of stream */ } else throw e; }

When it happens

Trigger: Calling next() more times than hasNext() returned true, or continuing iteration after isDone(); typically a missing hasNext() check in the consumer loop.

Common situations: Manual while-loops over AsyncGenerator iterators without hasNext(); code that stores the iterator and resumes pulling after completion; off-by-one loops around streamed LLM results.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• AppTypeNotSupport
• Failed to parse any valid result from streaming response
• Failed to build JSON-RPC streaming payload
• Async tool execution failed
• Tool execution was cancelled

AI-assisted analysis of alibaba/spring-ai-alibaba@f82da0b50f (2026-09-09). Data as JSON: /api/errors/09b432952e03ee7e. Report an issue: GitHub.