siyuan-note/siyuan · error

decode image failed

Error message

decode image failed: %s

What it means

Identical message to 2211 but thrown at kernel/util/openai.go:787 after imaging.Decode (with auto-orientation applied) fails, i.e. the header parsed via DecodeConfig but the full pixel data cannot be decoded by the imaging library. The library-specific reason is appended to the message.

Solutions

1. Re-export/re-encode the image with a standard tool (e.g. convert to baseline JPEG or PNG) and retry
2. Check the file size against the source to detect truncation; re-sync or re-download the asset
3. Open the file in a viewer to confirm it is valid before sending it to the AI feature
4. Inspect the appended reason in the message to identify the specific decoder complaint

Example fix

// before: trusting the header parse
img, err := prepareImage(truncatedBytes, "image/jpeg", ...)
// after: verify full decodability first
if _, err := imaging.Decode(bytes.NewReader(truncatedBytes)); err != nil {
    return fmt.Errorf("source image is corrupt: %w", err)
}
img, err := prepareImage(truncatedBytes, "image/jpeg", ...)

if _, err := imaging.Decode(bytes.NewReader(data)); err != nil {
    return fmt.Errorf("source image is corrupt: %w", err)
}

When it happens

Trigger: Feeding an image whose full decode fails even though DecodeConfig succeeded: truncated pixel data, corrupt IDAT/scan segments, unsupported EXIF-heavy or progressive variants, or CMYK JPEGs the decoder rejects.

Common situations: Partially synced asset files; images stripped or mangled by an external processor; exotic JPEG variants (CMYK, lossless) or animated WebP edge cases failing imaging.Decode.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• unsupported or invalid image
• encode image failed
• generated image exceeds size limit
• generated image is empty
• generated image is invalid

AI-assisted analysis of siyuan-note/siyuan@9f775e8a12 (2026-09-19). Data as JSON: /api/errors/88a6847d1525d5e2. Report an issue: GitHub.

Appendix: source

Thrown at kernel/util/openai.go:787

	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),
		}, nil
	}
	if needsResize {
		decoded = imaging.Fit(decoded, maxEdge, maxEdge, imaging.Lanczos)
	}
	bounds = decoded.Bounds()
	if mimeType == "image/png" || mimeType == "image/webp" {
		var output bytes.Buffer

View on GitHub (pinned to 9f775e8a12)