invoke-ai/InvokeAI · error · ExternalProviderRequestError

DashScope async response contained no images: {output}

Error message

DashScope async response contained no images: {output}

What it means

The async task reported SUCCEEDED and 'results' was a list, but iterating it produced zero downloadable images: every entry either wasn't a dict, or lacked both a usable 'url' string and 'b64_image' string. The provider raises ExternalProviderRequestError with the output payload.

Source

Thrown at invokeai/app/services/external_generation/providers/alibabacloud.py:281

        if not isinstance(results, list):
            raise ExternalProviderRequestError(f"DashScope async response missing results: {output}")

        images: list[ExternalGeneratedImage] = []
        for result in results:
            if not isinstance(result, dict):
                continue
            url = result.get("url")
            if isinstance(url, str) and url:
                pil_image = self._download_image(url)
                images.append(ExternalGeneratedImage(image=pil_image, seed=request.seed))
                continue
            b64_image = result.get("b64_image")
            if isinstance(b64_image, str) and b64_image:
                pil_image = decode_image_base64(b64_image)
                images.append(ExternalGeneratedImage(image=pil_image, seed=request.seed))

        if not images:
            raise ExternalProviderRequestError(f"DashScope async response contained no images: {output}")

        return ExternalGenerationResult(
            images=images,
            seed_used=request.seed,
            provider_request_id=request_id,
            provider_metadata={"model": request.model.provider_model_id},
        )

    def _download_image(self, url: str) -> PILImageType:
        """Download an image from a URL and return it as a PIL Image, with a size cap."""
        try:
            response = requests.get(url, timeout=_DOWNLOAD_TIMEOUT, stream=True)
        except requests.RequestException as exc:
            raise ExternalProviderRequestError(f"Failed to download image from DashScope: {exc}") from exc

        with response:
            if not response.ok:
                raise ExternalProviderRequestError(

View on GitHub (pinned to 0b6a024f2f)

Solutions

  1. Inspect the embedded output to see the actual keys in each result entry
  2. If results are empty [], retry the generation — the task 'succeeded' without producing images
  3. Extend/patch _parse_async_response to read alternate keys (e.g. 'image_url', nested 'code') for your custom model
  4. Switch the model to _SYNC_MODELS if it actually supports the synchronous multimodal API
  5. Verify the DashScope region/API version matches the documented async image-generation schema

Example fix

// before
url = result.get("url")
if isinstance(url, str) and url:
    ...
// after
url = result.get("url") or result.get("image_url") or result.get("code")
if isinstance(url, str) and url.startswith("http"):
    ...
Defensive patterns

Strategy: validation

Validate before calling

def results_look_valid(output: dict) -> bool:
    results = output.get("results")
    return isinstance(results, list) and any(
        isinstance(r, dict) and (r.get("url") or r.get("b64_image")) for r in results
    )

Type guard

def result_has_image(result: dict) -> bool:
    return isinstance(result, dict) and (
        isinstance(result.get("url"), str) and bool(result["url"])
        or isinstance(result.get("b64_image"), str) and bool(result["b64_image"])
    )

Try / catch

try:
    result = provider.generate(request)
except ExternalProviderRequestError as e:
    if "contained no images" in str(e):
        log.warning("Async task produced zero images; retrying once")
        result = provider.generate(request)
    else:
        raise

Prevention

When it happens

Trigger: results entries use a different URL key (e.g. 'image_url' or 'code' with a merged URL); results contain error objects; DashScope returned success with empty results [].

Common situations: Custom async models with a result schema unlike wan/wuye image APIs; DashScope partial success returning empty results; region/API revision where result URLs are nested under 'code' instead of 'url'.

Related errors

AI-assisted analysis of invoke-ai/InvokeAI@0b6a024f2f (2026-08-29). Data as JSON: /api/errors/36c59a4a4a2d13ba. Report an issue: GitHub.