dotnet/wpf · error · NotSupportedException

SR.Converter_ConvertToNotSupported

Error message

SR.Converter_ConvertToNotSupported

What it means

PathFigureCollectionConverter.ConvertTo throws NotSupportedException with SR.Converter_ConvertToNotSupported when the target PathFigureCollection cannot be serialized to a string (CanSerializeToString() returns false), e.g. it contains figures that do not round-trip to the compact path string syntax.

Solutions

1. Check CanSerializeToString() before converting and fall back to another serialization (e.g. XAML/BAML) when false.
2. Ensure the collection is non-empty and its figures are in a serializable state before converting.
3. Catch NotSupportedException and serialize the object graph via a different mechanism.

Example fix

// before
var s = (string)converter.ConvertTo(ctx, culture, figures, typeof(string));
// after
if (!figures.CanSerializeToString())
{
    throw new InvalidOperationException("This PathFigureCollection cannot be converted to a string");
}
var s = (string)converter.ConvertTo(ctx, culture, figures, typeof(string));

if (figures.CanSerializeToString())
{
    var s = (string)converter.ConvertTo(null, culture, figures, typeof(string));
}

try
{
    return (string)converter.ConvertTo(ctx, culture, figures, typeof(string));
}
catch (NotSupportedException)
{
    return SerializeViaXaml(figures); // fallback serializer
}

When it happens

Trigger: Calling ConvertTo(instance, typeof(string)) on a PathFigureCollection whose CanSerializeToString() is false, typically with an empty collection or figures unsupported by the string format.

Common situations: Serializing a dynamically built or emptied PathFigureCollection; XAML serialization of Path figures that were constructed programmatically in a non-serializable state; round-tripping shapes between designer and code.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• SR.Converter_ConvertToNotSupported
• Cannot convert from type.
• Cannot convert to type.
• Cannot convert to type.
• SR.Converter_ConvertToNotSupported

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/ccb99969d275a092. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Generated/PathFigureCollectionConverter.cs:137

        /// </exception>
        /// <param name="context"> The ITypeDescriptorContext for this call. </param>
        /// <param name="culture"> The CultureInfo which is respected when converting. </param>
        /// <param name="value"> The object to convert to an instance of "destinationType". </param>
        /// <param name="destinationType"> The type to which this will convert the PathFigureCollection instance. </param>
        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
        {
            if (destinationType != null && value is PathFigureCollection)
            {
                PathFigureCollection instance = (PathFigureCollection)value;

                if (destinationType == typeof(string))
                {
                    // When invoked by the serialization engine we can convert to string only for some instances
                    if (context != null && context.Instance != null)
                    {
                        if (!instance.CanSerializeToString())
                        {
                            throw new NotSupportedException(SR.Converter_ConvertToNotSupported);
                        }
                    }

                    // Delegate to the formatting/culture-aware ConvertToString method.
                    return instance.ConvertToString(null, culture);
                }
            }

            // Pass unhandled cases to base class (which will throw exceptions for null value or destinationType.)
            return base.ConvertTo(context, culture, value, destinationType);
        }
    }
}

View on GitHub (pinned to 81131a70a4)