stride3d/stride · error · ArgumentException

Invalid type [ ]. Type must be assignable to Asset

Error message

Invalid type [{0}]. Type must be assignable to Asset

What it means

The AssetImporterParameters constructor that takes a set of supported types validates each type is assignable to Asset; passing any non-asset type (or an interface/abstract-only set) throws ArgumentException naming 'supportedTypes'. It guards the importer's output-type selection map.

Solutions

1. Ensure every element of supportedTypes is a class deriving from Stride.Core.Assets.Asset
2. Fix the type passed at the construction site (check generic/reflection code)
3. Add a pre-check with typeof(Asset).IsAssignableFrom(t) before constructing
4. Remove placeholder/abstract types that are not concrete asset outputs

Example fix

// before
new AssetImporterParameters(new[] { typeof(object) });
// after
new AssetImporterParameters(new[] { typeof(TextureAsset) }); // derives from Asset

foreach (var t in supportedTypes)
    if (t == null || !typeof(Asset).IsAssignableFrom(t))
        throw new ArgumentException($"{t} is not an Asset");

static bool IsAssetType(Type t) => t != null && typeof(Asset).IsAssignableFrom(t);

try { var p = new AssetImporterParameters(supportedTypes); }
catch (ArgumentException ex) when (ex.ParamName == "supportedTypes")
{ log.Error($"Invalid importer type: {ex.Message}"); }

When it happens

Trigger: Constructing AssetImporterParameters with a supportedTypes collection containing e.g. typeof(object), a custom non-Asset class, a struct, or null entries.

Common situations: Typo'd generic argument when wiring an importer; using a ViewModel/DTO type instead of the asset type; reflection-based code picking the wrong type from an assembly.

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

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AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/5757e3ad118d1878. Report an issue: GitHub.

Appendix: source

Thrown at sources/assets/Stride.Core.Assets/AssetImporterParameters.cs:48

    /// <param name="supportedTypes">The supported types.</param>
    public AssetImporterParameters(params Type[] supportedTypes) : this((IEnumerable<Type>)supportedTypes)
    {
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="AssetImporterParameters"/> class.
    /// </summary>
    /// <param name="supportedTypes">The supported types.</param>
    /// <exception cref="System.ArgumentNullException">supportedTypes</exception>
    /// <exception cref="System.ArgumentException">Invalid type [{0}]. Type must be assignable to Asset.ToFormat(type);supportedTypes</exception>
    public AssetImporterParameters(IEnumerable<Type> supportedTypes) : this()
    {
        ArgumentNullException.ThrowIfNull(supportedTypes);
        foreach (var type in supportedTypes)
        {
            if (!typeof(Asset).IsAssignableFrom(type))
            {
                throw new ArgumentException("Invalid type [{0}]. Type must be assignable to Asset".ToFormat(type), nameof(supportedTypes));
            }
            SelectedOutputTypes[type] = true;
        }
    }

    /// <summary>
    /// Gets the import input parameters.
    /// </summary>
    /// <value>The import input parameters.</value>
    public PropertyCollection InputParameters { get; private set; }

    /// <summary>
    /// Gets the selected output types.
    /// </summary>
    /// <value>The selected output types.</value>
    public Dictionary<Type, bool> SelectedOutputTypes { get; private set; }

    /// <summary>

View on GitHub (pinned to 96fad776d2)