stride3d/stride · error · Exception

Can not construct gizmo of type

Error message

Can not construct gizmo of type {gizmoType}, it does not have a constructor taking a single EntityComponent

What it means

DispatcherGizmo.Update instantiates a gizmo object via Activator.CreateInstance when the edited component type changes. Gizmo types must expose a constructor taking exactly one EntityComponent parameter; if the registered gizmo type's constructor does not match, reflection-based construction is impossible and a plain Exception is thrown.

Solutions

1. Add a constructor to the gizmo type accepting a single EntityComponent (or the exact component type registered) and delegate to the base constructor.
2. Check the gizmo type's registration/attribute points at the intended gizmo class, not an abstract helper type.
3. Unit-test gizmo construction with Activator.CreateInstance in a plugin's startup to fail early.

Example fix

// before
public class MyGizmo : EntityGizmo<MyComponent>
{
    public MyGizmo() { } // no EntityComponent ctor
}
// after
public class MyGizmo : EntityGizmo<MyComponent>
{
    public MyGizmo(EntityComponent component) : base(component) { }
}

if (gizmoType.GetConstructor(new[] { typeof(EntityComponent) }) == null)
    throw new InvalidOperationException($"{gizmoType} must have a single EntityComponent constructor.");

bool IsValidGizmoType(Type t) => !t.IsAbstract && t.GetConstructor(new[] { typeof(EntityComponent) }) != null;

try { currentGizmo = (EntityGizmo<TComponent>)Activator.CreateInstance(gizmoType, Component); }
catch (Exception ex) { log.Error($"Bad gizmo type {gizmoType}: {ex.Message}"); }

When it happens

Trigger: Registering or attributing a custom EntityGizmo<TComponent> whose constructor signature differs (e.g. parameterless ctor, extra parameters, or ctor taking a derived component type not matching typeof(EntityComponent) exactly for the reflection probe).

Common situations: Writing a custom gizmo for a custom entity component and forgetting the (EntityComponent) constructor; copy-pasting a gizmo class and changing its constructor; signature drift after refactoring base classes.

Related errors

• The associated asset type does not have a public…
• Type [ ] is not a primitive
• Type [ ] is not a primitive
• Type has no empty ctor
• IEntityGizmo ' ' must have a constructor with exactly one…

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/1126dc18e7277f33. Report an issue: GitHub.

Appendix: source

Thrown at sources/editor/Stride.Assets.Presentation/AssetEditors/Gizmos/DispatcherGizmo.cs:95

            if (currentGizmoType != gizmoType)
            {
                // Delete the old gizmo
                if (currentGizmo != null)
                {
                    currentGizmo.Dispose();
                    currentGizmo = null;
                }

                // Create the new gizmo
                if (gizmoType != null && typeof(IGizmo).IsAssignableFrom(gizmoType))
                {
                    if (gizmoType.GetConstructor(new[] { typeof(EntityComponent) }) != null)
                    {
                        currentGizmo = (EntityGizmo<TComponent>)Activator.CreateInstance(gizmoType, Component);
                    }
                    else
                    {
                        throw new Exception($"Can not construct gizmo of type {gizmoType}, it does not have a constructor taking a single {nameof(EntityComponent)}");
                    }
                }

                // Initialize the new gizmo
                currentGizmo?.Initialize(Services, EditorScene);

                // Set the selected and enabled state of the gizmo
                IsSelected = IsSelected;
                IsEnabled = IsEnabled;
            }
            currentGizmoType = gizmoType;

            // update the current gizmo
            currentGizmo?.Update();
        }

        protected override void Destroy()
        {

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