dotnet/wpf · error · ArgumentException

SR.Format(SR.InvalidPropertyValue, value…

Error message

SR.Format(SR.InvalidPropertyValue, value, dependencyProperty.Name)

What it means

During LoadOptimizedTemplateContent, ReceivePropertySet validates that a value read for a dependency property is acceptable via DependencyProperty.IsValidValue. If the value is neither valid for the property nor a MarkupExtension/DeferredReference (binding-style value), an ArgumentException is thrown. This protects against templates assigning out-of-range or wrong-typed values to dependency properties.

Solutions

Fix the value in the template XAML so it is valid for the dependency property (correct type/range/enum).
Use a Binding/TemplateBinding or MarkupExtension if the value must be computed dynamically.
Check the dependency property's metadata ValidateValueCallback for constraints and satisfy them.

Example fix

<!-- before -->
<Setter Property="FontSize" Value="abc"/>
<!-- after -->
<Setter Property="FontSize" Value="14"/>

Defensive patterns

Strategy: validation

Validate before calling

if (!dp.IsValidValue(value) && !(value is MarkupExtension || value is DeferredReference))
    throw new ArgumentException($"Invalid value for {dp.Name}");

Type guard

static bool IsValidFor(DependencyProperty dp, object v) => dp.IsValidValue(v) || v is MarkupExtension || v is DeferredReference;

Try / catch

try { LoadTemplateContent(); } catch (ArgumentException ex) { Log(ex.Message); /* fix XAML */ }

Prevention

Validate template attribute values against the dependency property's type and validation callback.
Prefer compiled/typed XAML tooling that catches these at build time.
Use bindings or markup extensions for dynamically computed values.

When it happens

Trigger: A compiled template's optimized content sets a dependency property to a value that fails IsValidValue (wrong type or outside validation, e.g. a negative value on a property with a validation callback) and the value is not a Binding/TemplateBinding/MarkupExtension/deferred reference.

Common situations: XAML in a template supplying an invalid attribute value (bad enum string, wrong unit, mismatched type); resource/dispatch issues where a StaticResource resolves to an invalid value at template load; tooling-generated XAML with type errors.

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

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/d98427360c5a1c15. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/FrameworkTemplate.cs:835

                        ConverterParameter = templateBindingExtension.ConverterParameter
                    };

                    value = binding;

                }
                else
                {
                    Debug.Fail("We do not have support for DynamicResource within unshared template content");
                }
            }

            bool isMarkupExtension = value is MarkupExtension;
            // Value needs to be valid for the DP, or Binding/MultiBinding/PriorityBinding/TemplateBinding.
            if (!dependencyProperty.IsValidValue(value))
            {
                if (!isMarkupExtension && !(value is DeferredReference))
                {
                    throw new ArgumentException(SR.Format(SR.InvalidPropertyValue, value, dependencyProperty.Name));
                }
            }

            parentTemplateValues[dependencyProperty] = value;

            dependencyObject.ProvideSelfAsInheritanceContext(value, dependencyProperty);

            EffectiveValueEntry entry = new EffectiveValueEntry(dependencyProperty)
            {
                BaseValueSourceInternal = BaseValueSourceInternal.ParentTemplate,
                Value = value
            };

            if (isMarkupExtension)
            {
                // entry will be updated to hold the value
                StyleHelper.GetInstanceValue(
                            StyleHelper.TemplateDataField,

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