AvaloniaUI/Avalonia · error · InvalidOperationException

Cannot animate direct property {property} on {display}.

Error message

Cannot animate direct property {property} on {display}.

What it means

Thrown by Transitions.Validate when a transition added to a Transitions collection targets a direct (non-styled) AvaloniaProperty. Avalonia's animation system can only bind styled properties, so animating a direct property is unsupported and rejected at insertion time.

Source

Thrown at src/Avalonia.Base/Animation/Transitions.cs:29

    {
        /// <summary>
        /// Initializes a new instance of the <see cref="Transitions"/> class.
        /// </summary>
        public Transitions()
        {
            ResetBehavior = ResetBehavior.Remove;
            Validator = this;
        }

        void IAvaloniaListItemValidator<ITransition>.Validate(ITransition item)
        {
            Dispatcher.UIThread.VerifyAccess();

            var property = item.Property;
            if (property.IsDirect)
            {
                var display = item is TransitionBase transition ? transition.DebugDisplay : item.ToString();
                throw new InvalidOperationException($"Cannot animate direct property {property} on {display}.");
            }
        }
    }
}

View on GitHub (pinned to 11c5427268)

Solutions

1. Target only styled properties (registered via AvaloniaProperty.Register) in transitions.
2. If you own the property, re-register it as styled, or wrap it so animation goes through a styled property.
3. Remove the offending transition from the collection.

Example fix

// before
control.Transitions = new Transitions
{
    new DoubleTransition { Property = MyControl.SomeDirectProperty, Duration = TimeSpan.FromSeconds(0.2) }
};

// after
control.Transitions = new Transitions
{
    new DoubleTransition { Property = Visual.OpacityProperty, Duration = TimeSpan.FromSeconds(0.2) }
};

if (transition.Property.IsDirect)
    throw new InvalidOperationException($"Cannot animate direct property {transition.Property}");

static bool IsAnimatable(AvaloniaProperty p) => !p.IsDirect;

try { control.Transitions = new Transitions { transition }; }
catch (InvalidOperationException ex) when (ex.Message.Contains("direct property"))
{ /* pick a styled property or drop the transition */ }

When it happens

Trigger: Adding a transition whose Property is a DirectProperty (e.g. a class registered via RegisterDirect) to a control's Transitions list; binding a transition to a property declared as direct.

Common situations: Mistakenly pointing a DoubleTransition at a direct property like a POCO-style getter/setter property; upgrading a control whose property was changed from styled to direct.

Related errors

• Transition has no property specified.
• Transition has no property specified.
• Transition elements have different parents.
• Cannot determine visual parent.
• Animation has no key frames

AI-assisted analysis of AvaloniaUI/Avalonia@11c5427268 (2026-08-13). Data as JSON: /api/errors/d07919b6b5df0672. Report an issue: GitHub.