dotnet/wpf · error · ArgumentException

SR.PropertyNotBindable (formatted with dp.Name)

Error message

SR.PropertyNotBindable (formatted with dp.Name)

What it means

MultiBindingExpression.CreateBindingExpression throws ArgumentException when the target DependencyProperty cannot accept data binding: its FrameworkPropertyMetadata has IsDataBindingAllowed == false or the property is read-only. Applying SetBinding/SetMultiBinding to such a property is rejected with the property name in the message.

Solutions

1. Choose a writable, bindable dependency property as the binding target
2. If the property is read-only, bind a related writable property or use OneWayToSource on a different target
3. Check dp.ReadOnly and FrameworkPropertyMetadata.IsDataBindingAllowed before calling SetBinding

Example fix

// before
textBlock.SetBinding(TextBlock.ActualWidthProperty, multiBinding); // read-only
// after
textBlock.SetBinding(TextBlock.WidthProperty, multiBinding); // bindable target

var md = dp.GetMetadata(d.DependencyObjectType) as FrameworkPropertyMetadata;
bool bindable = md != null && md.IsDataBindingAllowed && !dp.ReadOnly;

bool IsBindable(DependencyObject d, DependencyProperty dp) => dp.GetMetadata(d.DependencyObjectType) is FrameworkPropertyMetadata md && md.IsDataBindingAllowed && !dp.ReadOnly;

try { BindingOperations.SetBinding(d, dp, multiBinding); } catch (ArgumentException ex) when (ex.ParamName == "dp") { /* property not bindable */ }

When it happens

Trigger: Calling BindingOperations.SetBinding(d, dp, new MultiBinding(...)) where dp is a read-only dependency property (e.g. registered with ReadOnly) or has metadata blocking binding; using a MultiBinding on a property with FrameworkPropertyMetadata options like NotDataBindable.

Common situations: Targeting read-only properties such as ActualWidth/IsLoaded; typos choosing the wrong DependencyProperty field; custom controls that registered a property read-only but a template tries to bind it.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Animation_DependencyPropertyIsNotAnimatable
• Animation_CalculatedValueIsInvalidForProperty
• Animation_ChildMustBeKeyFrame
• Animation_UnrecognizedHandoffBehavior
• InvalidEnumArgumentException for value (TextTrimming)

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/db03143f781f3536. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Data/MultiBindingExpression.cs:159

    internal override bool IsParentBindingUpdateTriggerDefault
    {
        get { return (ParentMultiBinding.UpdateSourceTrigger == UpdateSourceTrigger.Default); }
    }

    //------------------------------------------------------
    //
    //  Internal Methods
    //
    //------------------------------------------------------

    // Create a new BindingExpression from the given Binding description
    internal static MultiBindingExpression CreateBindingExpression(DependencyObject d, DependencyProperty dp, MultiBinding binding, BindingExpressionBase owner)
    {
        FrameworkPropertyMetadata fwMetaData = dp.GetMetadata(d.DependencyObjectType) as FrameworkPropertyMetadata;

        if ((fwMetaData != null && !fwMetaData.IsDataBindingAllowed) || dp.ReadOnly)
            throw new ArgumentException(SR.Format(SR.PropertyNotBindable, dp.Name), nameof(dp));

        // create the BindingExpression
        MultiBindingExpression bindExpr = new MultiBindingExpression(binding, owner);

        bindExpr.ResolvePropertyDefaultSettings(binding.Mode, binding.UpdateSourceTrigger, fwMetaData);

        return bindExpr;
    }

        // Attach to things that may require tree context (parent, root, etc.)
        private void AttachToContext(bool lastChance)
    {
        DependencyObject target = TargetElement;
        if (target == null)
            return;

        Debug.Assert(ParentMultiBinding.Converter != null || !String.IsNullOrEmpty(EffectiveStringFormat),
                "MultiBindingExpression should not exist if its bind does not have a valid converter.");

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