d2phap/ImageGlass · error · FormatException

IGE: Unsupported image format.

Error message

IGE: Unsupported image format.

What it means

Thrown by MagickCodec.SaveAsync when CanWrite(destFilePath) is false. CanWrite delegates to MagickFormatInfo.Create(destFilePath)?.SupportsWriting, which resolves the encoder from the destination file extension. The check runs before any decode, so the source image is irrelevant; only the destination extension matters.

Source

Thrown at source/ImageGlass.Lib/Common/Photoing/Codecs/MagickCodecs/MagickCodec.cs:770

    /// Save the photo to file.
    /// </summary>
    /// <param name="meta">Source metadata</param>
    /// <param name="destFilePath">Destination filename</param>
    /// <param name="options">Options for reading image file</param>
    /// <param name="transform">Changes for writing image file</param>
    /// <param name="quality">Quality</param>
    /// <exception cref="Exception"></exception>
    public static async Task SaveAsync(PhotoMetadata meta, string destFilePath, PhotoReadOptions options,
        PhotoTransform? transform = null, uint quality = 100, CancellationToken token = default)
    {
        var destExt = Path.GetExtension(destFilePath);

        try
        {
            // 1. check if format is supported
            if (!CanWrite(destFilePath))
            {
                throw new FormatException("IGE: Unsupported image format.");
            }


            // 2. read the photo
            var settings = ParseSettings(options, true, meta.FilePath);
            using var result = await DecodeImageAsync(meta, options with
            {
                // Magick.NET auto-corrects the rotation when saving,
                // so we don't need to correct it manually.
                CorrectRotation = false,
            }, settings, transform, token);


            // 3. save the photo to file
            if (result.MultiFrames is not null)
            {
                // convert GIF to non-GIF formats, we need to coalesce all frames
                if (meta.FileExtension.Equals(".gif", StringComparison.OrdinalIgnoreCase)

View on GitHub (pinned to 4a3c4fecef)

Solutions

1. Call MagickCodec.CanWrite(destFilePath) before SaveAsync and fall back to a known-good extension such as .png or .jpg.
2. Verify the destination has a recognized image extension and is spelled/cased correctly.
3. If HEIC/AVIF write is required, deploy the Magick.NET native asset that includes the encoder for that runtime.
4. Surface the unsupported extension to the user in the Save dialog so they can pick a supported format.

Example fix

// before
await MagickCodec.SaveAsync(meta, destFilePath, options, transform, quality, token);

// after
if (!MagickCodec.CanWrite(destFilePath))
{
    destFilePath = Path.ChangeExtension(destFilePath, ".png");
}
await MagickCodec.SaveAsync(meta, destFilePath, options, transform, quality, token);

if (!MagickCodec.CanWrite(destFilePath))
    throw new InvalidOperationException($"No encoder for '{destFilePath}'.");

try { await MagickCodec.SaveAsync(meta, destFilePath, options, transform, quality, token); }
catch (FormatException ex) when (ex.Message.Contains("Unsupported image format"))
{ destFilePath = Path.ChangeExtension(destFilePath, ".png"); /* retry */ }

When it happens

Trigger: Calling SaveAsync with a destination whose extension has no Magick.NET encoder: an unknown/typo extension, an extension whose native encoder is not shipped in the loaded Magick.Native asset (e.g., HEIC/AVIF on some builds), or a path with no extension at all.

Common situations: User picks 'Save As' for a format the bundled Magick.NET build cannot write; cross-platform build differences where HEIC write is available on Windows but not Linux; saving to a file whose extension case or spelling does not map to a known MagickFormat.

Related errors

• IGE: Unsupported image format.
• The base64 content is invalid.
• IGE_002
• IGE: '{codec.CodecName}' could not write the image. {result.
• IGE: frame too large to encode.

AI-assisted analysis of d2phap/ImageGlass@4a3c4fecef (2026-08-13). Data as JSON: /api/errors/1ace0b025f544ee0. Report an issue: GitHub.