siyuan-note/siyuan · error

unsupported or invalid image:

Error message

unsupported or invalid image: 

What it means

image.DecodeConfig (header decode) failed after the mime check passed. Causes: corrupt header, truncated file, or a header that decodes but is structurally invalid. The underlying decoder error is appended.

Source

Thrown at kernel/util/openai.go:639

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) {
		return PreparedImage{}, fmt.Errorf("image exceeds pixel limit: %d", maxPixels)
	}

	decoded, err := imaging.Decode(bytes.NewReader(data), imaging.AutoOrientation(true))
	if err != nil {
		return PreparedImage{}, errors.New("decode image failed: " + err.Error())
	}
	bounds := decoded.Bounds()
	needsResize := maxEdge > 0 && (bounds.Dx() > maxEdge || bounds.Dy() > maxEdge)
	if !needsResize && bounds.Dx() == config.Width && bounds.Dy() == config.Height && mimeType != "image/gif" {
		return PreparedImage{
			Data:       data,
			MIMEType:   mimeType,
			Width:      bounds.Dx(),
			Height:     bounds.Dy(),
			SourceSize: len(data),

View on GitHub (pinned to 251596fc0d)

Solutions

1. Re-download or re-copy the asset.
2. Re-save the image with an editor (rewrites a clean header).
3. Convert to PNG/JPEG through a trusted tool.
4. Drop the unreadable asset from the vision context.

if _, _, err := image.DecodeConfig(bytes.NewReader(data)); err != nil {
    return errors.New("image header unreadable; re-export the asset")
}

img, err := util.PrepareModelImage(data, maxB, maxP, maxE)
if err != nil {
    log.Warnf("drop unreadable image from vision context: %s", err)
    continue
}

When it happens

Trigger: Truncated download (e.g. partial PNG header); file with a valid magic but corrupt IHDR/SOIF; copy interrupted mid-file; exFAT/FAT corruption.

Common situations: Partial image download; copy/paste interrupted; asset exported with a broken header by a buggy tool.

Related errors

• decode image failed:
• image data is empty
• image exceeds size limit: %d bytes
• SVG images are not accepted by multimodal models
• unsupported image type: %s

AI-assisted analysis of siyuan-note/siyuan@251596fc0d (2026-08-12). Data as JSON: /api/errors/ba81e870a04f4e3d. Report an issue: GitHub.