siyuan-note/siyuan · error

image data is empty

Error message

image data is empty

What it means

PrepareModelImage's first guard rejects nil/zero-length input before any detection. It means the caller passed an empty asset (failed download, zero-byte file, or nil pointer) to a multimodal model call.

Source

Thrown at kernel/util/openai.go:623

		err = fmt.Errorf("rerank returned %d indices for %d documents", len(indices), len(documents))
		return
	}
	seen := make(map[int]bool, len(indices))
	for _, index := range indices {
		if seen[index] {
			err = fmt.Errorf("rerank returned duplicate index %d", index)
			return
		}
		seen[index] = true
	}
	matched = true
	return
}

// PrepareModelImage 校验并按需缩放图片，尽量保留多模态模型支持的原始格式和图片质量。
func PrepareModelImage(data []byte, maxBytes, maxPixels, maxEdge int) (PreparedImage, error) {
	if len(data) == 0 {
		return PreparedImage{}, errors.New("image data is empty")
	}
	if maxBytes > 0 && len(data) > maxBytes {
		return PreparedImage{}, fmt.Errorf("image exceeds size limit: %d bytes", maxBytes)
	}
	mimeType := mimetype.Detect(data).String()
	if strings.Contains(mimeType, "svg") || bytes.Contains(bytes.ToLower(data[:min(len(data), 512)]), []byte("<svg")) {
		return PreparedImage{}, errors.New("SVG images are not accepted by multimodal models")
	}
	switch mimeType {
	case "image/gif", "image/jpeg", "image/png", "image/webp":
	default:
		return PreparedImage{}, fmt.Errorf("unsupported image type: %s", mimeType)
	}
	config, _, err := image.DecodeConfig(bytes.NewReader(data))
	if err != nil {
		return PreparedImage{}, errors.New("unsupported or invalid image: " + err.Error())
	}
	if config.Width < 1 || config.Height < 1 || maxPixels > 0 && int64(config.Width)*int64(config.Height) > int64(maxPixels) {

View on GitHub (pinned to 251596fc0d)

Solutions

1. Verify the source asset exists and is non-empty before calling.
2. Check that the upstream download/read error is not being swallowed.
3. Skip empty attachments instead of forwarding them to the model.

Example fix

// before
img, err := util.PrepareModelImage(maybeEmptyBytes, maxB, maxP, maxE)

// after
if len(raw) == 0 { return errors.New("no image content") }
img, err := util.PrepareModelImage(raw, maxB, maxP, maxE)

if len(data) == 0 { return errors.New("image is empty") }
img, err := util.PrepareModelImage(data, maxBytes, maxPixels, maxEdge)

func HasImageContent(data []byte) bool { return len(data) > 0 }

When it happens

Trigger: Calling a vision/multimodal model with a block whose image asset is missing or zero bytes; passing the result of a failed read/download that was swallowed.

Common situations: Asset path wrong so the read returns empty; network image download failed silently; PDF/image attachment not yet downloaded.

Related errors

• image exceeds size limit: %d bytes
• SVG images are not accepted by multimodal models
• unsupported image type: %s
• unsupported or invalid image:
• image exceeds pixel limit: %d

AI-assisted analysis of siyuan-note/siyuan@251596fc0d (2026-08-12). Data as JSON: /api/errors/931951e2942c8885. Report an issue: GitHub.