Tichau/FileConverter · error · Exception

The conversion preset must be valid.

Error message

The conversion preset must be valid.

What it means

ConversionJob_Gif.Convert() throws Exception when this.ConversionPreset is null before delegating to its child jobs (an optional pngConversionJob to normalize the input image and a ConversionJob_FFMPEG that builds the GIF). The job constructs its FFMPEG child from this.ConversionPreset in Initialize(), so a null preset would propagate NREs into the child; the guard fails fast instead. Like the sibling jobs, the real ctor blocks null presets, so this fires only via the parameterless design-mode ctor or direct/reflection invocation of Convert().

Source

Thrown at Application/FileConverter/ConversionJobs/ConversionJob_Gif.cs:70

                this.pngConversionJob.PrepareConversion(this.intermediateFilePath);

                inputFilePath = this.intermediateFilePath;
            }
            else
            {
                inputFilePath = this.InputFilePath;
            }

            // Convert png file into ico.
            this.gifConversionJob = new ConversionJob_FFMPEG(this.ConversionPreset, inputFilePath);
            this.gifConversionJob.PrepareConversion(this.OutputFilePath);
        }

        protected override void Convert()
        {
            if (this.ConversionPreset == null)
            {
                throw new Exception("The conversion preset must be valid.");
            }

            Task updateProgress = this.UpdateProgress();

            if (this.pngConversionJob != null)
            {
                this.UserState = Properties.Resources.ConversionStateReadIntputImage;

                Diagnostics.Debug.Log(string.Empty);
                Diagnostics.Debug.Log("Convert image to PNG (intermediate format).");
                this.pngConversionJob.StartConversion();

                if (this.pngConversionJob.State != ConversionState.Done)
                {
                    this.ConversionFailed(this.pngConversionJob.ErrorMessage);
                    return;
                }
            }

View on GitHub (pinned to 6c157a411f)

Solutions

1. Construct via new ConversionJob_Gif(conversionPreset, inputFilePath) or ConversionJobFactory.Create.
2. Drive the job through PrepareConversion() + StartConversion(), not Convert().
3. Early-return in design-time when ConversionPreset is null.
4. Confirm preset loading succeeded before creating the job.

Example fix

// before
var job = new ConversionJob_Gif();
job.Convert(); // throws: preset null

// after
var job = ConversionJobFactory.Create(conversionPreset, inputFilePath);
job.PrepareConversion(outputFilePath);
job.StartConversion();

if (job == null || job.ConversionPreset == null)
{
    throw new InvalidOperationException(
        "ConversionJob_Gif requires a non-null ConversionPreset; use the (preset, inputFilePath) constructor.");
}
job.StartConversion();

private static bool HasValidPreset(ConversionJob job) => job != null && job.ConversionPreset != null;

try
{
    job.StartConversion();
}
catch (Exception ex) when (ex.Message.Contains("conversion preset must be valid"))
{
    logger.Error(ex, "GIF job created without a preset.");
    job = new ConversionJob_Gif(LoadPreset(), inputPath);
}

When it happens

Trigger: ConversionJob_Gif built via its parameterless ctor then Convert() invoked; or reflection calling Convert() on an instance whose preset is null. Initialize() already uses this.ConversionPreset to construct the FFMPEG child, so a null would also break initialization earlier.

Common situations: XAML design-time instantiation; unit tests exercising Convert() directly; a pipeline that created the GIF job before the image-output preset was loaded.

Related errors

• The conversion preset must be valid.
• The conversion preset must be valid.
• The conversion preset must be valid.
• The conversion preset must be valid.
• The conversion preset must be valid.

AI-assisted analysis of Tichau/FileConverter@6c157a411f (2026-08-13). Data as JSON: /api/errors/f003312a95158a8c. Report an issue: GitHub.