invoke-ai/InvokeAI · error · ExternalProviderRequestError

Failed to download image from DashScope: {exc}

Error message

Failed to download image from DashScope: {exc}

What it means

_download_image fetches generated image URLs with requests.get(stream=True). Any requests.RequestException (DNS failure, connection reset, TLS error, timeout after _DOWNLOAD_TIMEOUT=60s) is wrapped and re-raised as ExternalProviderRequestError with the underlying exception text.

Source

Thrown at invokeai/app/services/external_generation/providers/alibabacloud.py:295

                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(
                    f"Failed to download image from DashScope (status {response.status_code})"
                )

            content_length = response.headers.get("Content-Length")
            if content_length is not None:
                try:
                    if int(content_length) > _DOWNLOAD_MAX_BYTES:
                        raise ExternalProviderRequestError(
                            f"DashScope image exceeds {_DOWNLOAD_MAX_BYTES} byte cap (Content-Length={content_length})"
                        )
                except ValueError:
                    pass

            buffer = bytearray()

View on GitHub (pinned to 0b6a024f2f)

Solutions

  1. Retry the generation — the provider does not retry image downloads, only API calls
  2. Check egress/firewall rules so the app host can reach the DashScope CDN hosts
  3. Download promptly after generation; expired signed URLs cause connection/HTTP failures
  4. Verify DNS and proxy settings (HTTP_PROXY/HTTPS_PROXY) in the deployment environment
  5. Test the failing URL with curl from the same host to isolate network vs code issues

Example fix

// before
response = requests.get(url, timeout=_DOWNLOAD_TIMEOUT, stream=True)
// after
for attempt in range(3):
    try:
        response = requests.get(url, timeout=_DOWNLOAD_TIMEOUT, stream=True)
        break
    except requests.RequestException:
        if attempt == 2:
            raise
        time.sleep(2 ** attempt)
Defensive patterns

Strategy: retry

Validate before calling

import socket, requests
def can_reach_host(url: str) -> bool:
    try:
        host = requests.utils.urlparse(url).hostname
        socket.getaddrinfo(host, 443)
        return True
    except (socket.gaierror, ValueError):
        return False

Try / catch

try:
    result = provider.generate(request)
except ExternalProviderRequestError as e:
    if "Failed to download image from DashScope:" in str(e):
        log.warning("Transient image-download failure, retrying: %s", e)
        result = provider.generate(request)
    else:
        raise

Prevention

When it happens

Trigger: The image host is unreachable; the returned image URL has expired (DashScope URLs are time-limited); DNS/proxy issues in the deployment environment; network outage mid-generation; TLS interception by corporate proxies.

Common situations: Delaying image download until after DashScope's signed URL TTL expires (typically ~24h, but can be shorter); air-gapped/egress-restricted clusters where the app host cannot reach the CDN host; flaky container networking.

Related errors

AI-assisted analysis of invoke-ai/InvokeAI@0b6a024f2f (2026-08-29). Data as JSON: /api/errors/114116f4fab92c9d. Report an issue: GitHub.