dotnet/wpf · error · ArgumentException

SR.Format(SR.TemplateTargetTypeMismatch…

Error message

SR.Format(SR.TemplateTargetTypeMismatch, "ContentPresenter", templatedParent.GetType().Name)

What it means

DataTemplate.ValidateTemplatedParent throws ArgumentException when a DataTemplate's templated parent is not a ContentPresenter. DataTemplates may only be applied through a ContentPresenter host; other element types must use ControlTemplate or ItemsPanelTemplate.

Solutions

1. Use the DataTemplate only via ContentPresenter (e.g. ContentTemplate / ItemTemplate properties)
2. If templating a Control, declare a ControlTemplate instead
3. Check the host element: typeof(templatedParent) must be ContentPresenter before applying

Example fix

// before
button.Template = (DataTemplate)FindResource("itemTemplate"); // wrong kind
// after
button.Template = (ControlTemplate)FindResource("buttonTemplate");
// or: contentPresenter.ContentTemplate = (DataTemplate)FindResource("itemTemplate");

if (templatedParent is not ContentPresenter) throw new InvalidOperationException("DataTemplate requires a ContentPresenter templated parent");

bool CanApplyDataTemplate(object parent) => parent is ContentPresenter;

try { ValidateTemplatedParent(templatedParent); } catch (ArgumentException) { /* use ControlTemplate or a ContentPresenter host */ }

When it happens

Trigger: Calling ApplyTemplate/finding a template host where templatedParent is e.g. a Control (not ContentPresenter); assigning a DataTemplate as a ControlTemplate.

Common situations: Confusing ControlTemplate and DataTemplate in XAML; setting a DataTemplate where a ControlTemplate is expected (e.g. Template property of a Control); custom framework code invoking template validation with the wrong parent.

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 dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/cc91faddcba59f95. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/DataTemplate.cs:192

        //
        //  Protected Methods
        //
        //-------------------------------------------------------------------

        /// <summary>
        ///     Validate against the following rules
        ///     1. Must have a non-null feTemplatedParent
        ///     2. A DataTemplate must be applied to a ContentPresenter
        /// </summary>
        protected override void ValidateTemplatedParent(FrameworkElement templatedParent)
        {
            // Must have a non-null feTemplatedParent
            ArgumentNullException.ThrowIfNull(templatedParent);

            // A DataTemplate must be applied to a ContentPresenter
            if (!(templatedParent is ContentPresenter))
            {
                throw new ArgumentException(SR.Format(SR.TemplateTargetTypeMismatch, "ContentPresenter", templatedParent.GetType().Name));
            }
        }

        #endregion Protected Methods

        #region Data

        private object                  _dataType;
        private TriggerCollection       _triggers;

        #endregion Data
    }
}

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