stride3d/stride · error · InvalidOperationException

Cannot serialize an object of type

Error message

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

What it means

IdentifiableAssetPartReference.FillFromPart builds a lightweight reference (id only) from an actual asset part. The part must implement IIdentifiable so its Id can be captured; when it does not, the method throws InvalidOperationException because a reference cannot be formed without an identifier. This is a contract check protecting the serialization pipeline.

Solutions

Make the asset part class implement IIdentifiable (inheriting from the framework's Identifiable base) so it exposes an Id.
Pass the correct part object — the IIdentifiable asset part rather than a plain wrapper — to FillFromPart.
Guard the call with 'assetPart is IIdentifiable' and skip or log parts that cannot be referenced.
If a library type regressed, wrap or adapt it in your own IIdentifiable implementation carrying the id.

Example fix

// before
class MyPart { public Guid Id; ... } // not IIdentifiable
reference.FillFromPart(new MyPart());

// after
class MyPart : Identifiable { ... }
reference.FillFromPart(new MyPart());

Defensive patterns

Strategy: type-guard

Validate before calling

if (assetPart is not IIdentifiable)
    throw new ArgumentException("Asset part must implement IIdentifiable", nameof(assetPart));

Type guard

bool IsReferencablePart(object part) => part is IIdentifiable;

Try / catch

try { reference.FillFromPart(part); }
catch (InvalidOperationException) { log.Warn($"Skipping non-identifiable part {part.GetType().Name}"); }

Prevention

Derive all custom asset parts from the Identifiable base class
Assert parts implement IIdentifiable at registration time
Pass the part itself, not a wrapper, to FillFromPart
Add unit tests exercising the reference round-trip for custom parts

When it happens

Trigger: Calling FillFromPart with an object whose runtime type does not implement IIdentifiable — e.g. passing a plain model/effect object or a custom asset part that forgot to implement IIdentifiable while still being registered as an asset part.

Common situations: Custom asset part types added to an asset without implementing IIdentifiable; API changes between library versions where a part type lost its IIdentifiable implementation; wiring up wrong objects (a wrapper instead of the part) in custom editor tooling.

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

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/f27a21ac83959e70. Report an issue: GitHub.

Appendix: source

Thrown at sources/assets/Stride.Core.Assets/Serializers/IdentifiableAssetPartReference.cs:35

    /// Gets or sets the identifier of the asset part represented by this reference.
    /// </summary>
    public Guid Id { get; set; }

    /// <inheritdoc/>
    [DataMemberIgnore]
    public Type InstanceType { get; set; }

    /// <inheritdoc/>
    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;
    }
}

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