Comfy-Org/ComfyUI · error · ValueError

Invalid image payload – neither URL nor base64 data present.

Error message

Invalid image payload – neither URL nor base64 data present.

What it means

Raised while iterating the OpenAI image response data array: an individual image entry has neither b64_json nor url populated. The helper cannot obtain bytes for that image, so it fails with this ValueError instead of silently skipping an element.

Source

Thrown at comfy_api_nodes/nodes_openai.py:91

        ValueError: If the response is not valid.
    """
    # validate raw JSON response
    data = response.data
    if not data or len(data) == 0:
        raise ValueError("No images returned from API endpoint")

    # Initialize list to store image tensors
    image_tensors: list[torch.Tensor] = []

    # Process each image in the data array
    for img_data in data:
        if img_data.b64_json:
            img_io = BytesIO(base64.b64decode(img_data.b64_json))
        elif img_data.url:
            img_io = BytesIO()
            await download_url_to_bytesio(img_data.url, img_io, timeout=timeout)
        else:
            raise ValueError("Invalid image payload – neither URL nor base64 data present.")

        pil_img = Image.open(img_io).convert("RGBA")
        arr = np.asarray(pil_img).astype(np.float32) / 255.0
        image_tensors.append(torch.from_numpy(arr))

    # With size="auto" the API can return images whose dimensions differ by a few pixels within a single response
    # resize them to the first image's dimensions so they can be stacked into one batch.
    ref_h, ref_w = image_tensors[0].shape[:2]
    for i, t in enumerate(image_tensors):
        if t.shape[:2] != (ref_h, ref_w):
            samples = t.unsqueeze(0).movedim(-1, 1)
            samples = common_upscale(samples, ref_w, ref_h, "bilinear", "center")
            image_tensors[i] = samples.movedim(1, -1).squeeze(0)
    return torch.stack(image_tensors, dim=0)


class OpenAIDalle2(IO.ComfyNode):

View on GitHub (pinned to 1c6d8d45b3)

Solutions

  1. Log the offending img_data object to see which fields the endpoint actually returned
  2. If using a compatible/proxy endpoint, ensure it returns b64_json (set response_format='b64_json') or a valid url per entry
  3. Retry with n=1 to isolate whether only some entries in a batch are malformed
  4. Update or pin the api-node package if the endpoint schema changed and the node's pydantic model is stale

Example fix

// before
for img_data in data:
    if img_data.b64_json: ...
    elif img_data.url: ...
    else:
        raise ValueError("Invalid image payload ...")
// after (skip malformed entries, fail only if none decode)
valid = [d for d in data if d.b64_json or d.url]
if not valid:
    raise ValueError("No decodable images in API response")
Defensive patterns

Strategy: type-guard

Validate before calling

entries = [d for d in resp.data if getattr(d, "b64_json", None) or getattr(d, "url", None)]
if not entries:
    raise ValueError("no decodable image entries in response")

Type guard

def is_valid_image_entry(d) -> bool:
    return bool(getattr(d, "b64_json", None) or getattr(d, "url", None))

Try / catch

try:
    tensors = await openai_images_to_tensor(resp)
except ValueError as e:
    if "neither URL nor base64" in str(e):
        # endpoint schema issue: log the raw entry, switch response_format or provider
        raise
    raise

Prevention

When it happens

Trigger: An OpenAI (or compatible) image API response where a data[i] object exists but both b64_json and url fields are null/absent - often from third-party OpenAI-compatible endpoints with partial schema compliance or partial failures inside a multi-image (n>1) response.

Common situations: Using an OpenAI-compatible proxy or alternative provider behind /proxy/openai that returns placeholder data entries; partial failures inside a batch; API version drift where the field was renamed.

Related errors

AI-assisted analysis of Comfy-Org/ComfyUI@1c6d8d45b3 (2026-08-14). Data as JSON: /api/errors/a89ac8bfd2717706. Report an issue: GitHub.