stride3d/stride · error · InvalidOperationException

Cannot serialize an object of type

Error message

Cannot serialize an object of type {partType.Name} as an asset part reference: the type does not implement {typeof(IIdentifiable).Name}

What it means

IdentifiableAssetPartReference.GenerateProxyPart materializes a proxy instance of the given part type and assigns the stored Id to it. It requires the type to implement IIdentifiable; otherwise the generated instance cannot receive the Id and InvalidOperationException is thrown. Like FillFromPart, this enforces the identifiable contract on both ends of the reference round-trip.

Solutions

1. Make the part type implement IIdentifiable (derive from Identifiable) so GenerateProxyPart can assign the Id.
2. Pass the correct part Type — the identifiable one associated with the reference — to GenerateProxyPart.
3. Check typeof(IIdentifiable).IsAssignableFrom(partType) before calling and handle non-identifiable types separately.
4. Return null gracefully by ensuring Id == Guid.Empty only for intentionally empty references; fix the type for real parts.

Example fix

// before
var part = (AssetPart)reference.GenerateProxyPart(typeof(PlainPart));

// after
class PlainPart : Identifiable { ... } // or use the identifiable part type
var part = (AssetPart)reference.GenerateProxyPart(typeof(IdentifiablePart));

if (!typeof(IIdentifiable).IsAssignableFrom(partType))
    throw new ArgumentException($"{partType.Name} must implement IIdentifiable", nameof(partType));

bool IsIdentifiablePartType(Type t) => typeof(IIdentifiable).IsAssignableFrom(t);

try { return reference.GenerateProxyPart(partType); }
catch (InvalidOperationException) { log.Error($"Cannot proxy non-identifiable type {partType.Name}"); return null; }

When it happens

Trigger: Calling GenerateProxyPart(typeof(T)) where typeof(T) does not implement IIdentifiable — e.g. registering a reference for a part type that is not identifiable, or passing the wrong Type during proxy generation of a deserialized asset.

Common situations: Custom asset part types missing the IIdentifiable implementation on the deserialization side; refactorings that changed a part's base class; mismatched part types between the reference descriptor and the actual asset model.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Cannot serialize an object of type
• Unable to extract asset reference from object
• Unable to extract url reference from object
• The given container does not match the expected type.
• Unexpected arguments

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/86c898ac9ec8c64b. Report an issue: GitHub.

Appendix: source

Thrown at sources/assets/Stride.Core.Assets/Serializers/IdentifiableAssetPartReference.cs:44

    public override string ToString()
    {
        return $"{{AssetPartReference: {Id}}}";
    }

    /// <inheritdoc/>
    public void FillFromPart(object assetPart)
    {
        if (assetPart is not IIdentifiable identifiable)
            throw new InvalidOperationException($"Cannot serialize an object of type {assetPart.GetType().Name} as an asset part reference: the type does not implement {typeof(IIdentifiable).Name}");

        Id = identifiable?.Id ?? Guid.Empty;
    }

    /// <inheritdoc/>
    public object? GenerateProxyPart(Type partType)
    {
        if (!typeof(IIdentifiable).IsAssignableFrom(partType))
            throw new InvalidOperationException($"Cannot serialize an object of type {partType.Name} as an asset part reference: the type does not implement {typeof(IIdentifiable).Name}");

        if (Id == Guid.Empty)
            return null;

        var assetPart = (IIdentifiable)Activator.CreateInstance(partType)!;
        assetPart.Id = Id;
        return assetPart;
    }
}

View on GitHub (pinned to 96fad776d2)