deepset-ai/haystack · error · RuntimeError

Pipeline was cancelled; no result available.

Error message

Pipeline was cancelled; no result available.

What it means

Pipeline.result() raises RuntimeError if the pipeline's asyncio task was cancelled before completion, because there is no final output to return. This is distinct from a failed run (which re-raises the original exception).

Source

Thrown at haystack/core/pipeline/pipeline.py:100

                    return
                yield cast(StreamingChunk, item)  # at this point, item is guaranteed to be a StreamingChunk

        finally:
            if self._cancel_on_abandon:
                await self.aclose()

    @property
    def result(self) -> dict[str, Any]:
        """
        Final pipeline output dict, available only after a successful, complete run.

        Raises a `RuntimeError` if the pipeline has not finished or was cancelled. If the pipeline failed, re-raises the
        original exception.
        """
        if not self._task.done():
            raise RuntimeError("Pipeline has not finished; iterate the handle first.")
        if self._task.cancelled():
            raise RuntimeError("Pipeline was cancelled; no result available.")
        exc = self._task.exception()
        if exc is not None:
            raise exc
        return self._task.result()

    async def aclose(self) -> None:
        """
        Cancel the underlying pipeline task.

        Bounded by `_CLEANUP_TIMEOUT_SECONDS` so that components cannot block cleanup indefinitely.
        """
        if not self._task.done():
            self._task.cancel()
            with contextlib.suppress(BaseException):
                await asyncio.wait_for(self._task, timeout=self._CLEANUP_TIMEOUT_SECONDS)


class Pipeline(PipelineBase):

View on GitHub (pinned to e318778c9b)

Solutions

1. Guard result() access with a check whether the task was cancelled before calling it
2. Wrap result() in try/except RuntimeError and treat it as a cancelled run
3. Avoid cancelling the pipeline task if the final result is needed; or re-run the pipeline

Example fix

// before
print(handle.result())
// after
try:
    print(handle.result())
except RuntimeError:
    logger.warning("Pipeline run was cancelled; no result available.")

def was_cancelled(pipeline) -> bool:
    task = getattr(pipeline, "_task", None)
    return task is not None and task.cancelled()

try:
    result = handle.result()
except RuntimeError as e:
    if "cancelled" in str(e):
        logger.warning("Run cancelled; re-running or aborting")
    else:
        raise

When it happens

Trigger: Cancelling the run (e.g., asyncio.Task.cancel(), cancellation of the surrounding coroutine, timeout, KeyboardInterrupt in async context) and then calling result().

Common situations: asyncio.wait_for timeouts cancelling the pipeline task, user-initiated shutdown, pipeline.aclose() during a run, or cancellation propagated from a parent task.

Related errors

• Pipeline has not finished; iterate the handle first.
• MarkdownHeaderSplitter only works with text documents but co
• Error while unmarshalling serialized pipeline data. This is
• Component instance cannot be added to the pipeline more than
• A component named '{name}' already exists in this pipeline:

AI-assisted analysis of deepset-ai/haystack@e318778c9b (2026-08-30). Data as JSON: /api/errors/9deeb2ea03741839. Report an issue: GitHub.