stride3d/stride · error · ArgumentException

The parameter of this converter must be an instance of the…

Error message

The parameter of this converter must be an instance of the Thickness structure. Use {sd:Thickness (arguments)} to construct one.

What it means

NumericToThickness requires the ConverterParameter to be a WPF System.Windows.Thickness, whose four sides are each scaled by the numeric bound value. If the parameter is null or not a Thickness (e.g. a plain string), this ArgumentException is thrown. The message recommends the {sd:Thickness (arguments)} markup extension for constructing the parameter in XAML.

Solutions

  1. Set ConverterParameter="{sd:Thickness left, top, right, bottom}" in XAML
  2. Or supply a Thickness resource/static as the parameter
  3. Confirm the converter is NumericToThickness and the parameter type matches (Thickness, not Size or string)
  4. Move parameter construction into code-behind/view model if markup extensions are unavailable

Example fix

// before
Converter="{sd:NumericToThickness}" ConverterParameter="5,5,5,5"
// after
Converter="{sd:NumericToThickness}" ConverterParameter="{sd:Thickness 5,5,5,5}"
Defensive patterns

Strategy: type-guard

Validate before calling

bool IsValidThicknessParameter(object parameter) => parameter is System.Windows.Thickness;

Type guard

bool IsThickness(object p) => p is System.Windows.Thickness;

Try / catch

try
{
    return converter.Convert(value, typeof(Thickness), parameter, culture);
}
catch (ArgumentException)
{
    return new Thickness(0);
}

Prevention

When it happens

Trigger: ConverterParameter="10" or "10,10,10,10" (strings) instead of a Thickness instance; parameter omitted so it is null; passing a Size parameter to NumericToThickness by copy-paste mistake.

Common situations: Migrating from NumericToSize and reusing a string parameter; XAML tooling that only emits primitive parameters; misunderstanding that the parameter must be a struct instance, not text.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/58988538c8043e18. Report an issue: GitHub.

Appendix: source

Thrown at sources/presentation/Stride.Core.Presentation.Wpf/ValueConverters/NumericToThickness.cs:36

    public class NumericToThickness : ValueConverterBase<NumericToThickness>
    {
        /// <inheritdoc/>
        [NotNull]
        public override object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            double scalar;
            try
            {
                scalar = ConverterHelper.ConvertToDouble(value, culture);
            }
            catch (Exception exception)
            {
                throw new ArgumentException("The value of this converter must be convertible to a double.", exception);
            }

            if (!(parameter is Thickness))
            {
                throw new ArgumentException("The parameter of this converter must be an instance of the Thickness structure. Use {sd:Thickness (arguments)} to construct one.");
            }

            var thickness = (Thickness)parameter;
            var result = new Thickness(thickness.Left * scalar, thickness.Top * scalar, thickness.Right * scalar, thickness.Bottom * scalar);
            return result;
        }

        /// <inheritdoc/>
        public override object ConvertBack(object value, [NotNull] Type targetType, object parameter, CultureInfo culture)
        {
            if (!(value is Thickness))
            {
                throw new ArgumentException("The value of the ConvertBack method of this converter must be a an instance of the Thickness structure.");
            }
            if (!(parameter is Thickness))
            {
                throw new ArgumentException("The parameter of the ConvertBack method of this converter must be a an instance of the Thickness structure.");
            }

View on GitHub (pinned to 96fad776d2)