What causes "SR.Animation_NoTextChildren" in dotnet/wpf?

Remove text content from the animation element

dotnet/wpf · error · InvalidOperationException

SR.Animation_NoTextChildren

Error message

SR.Animation_NoTextChildren

What it means

ArgumentException from AddText on Point3DAnimationUsingKeyFrames: the IAddChild text path was invoked with text content, but key-frame animations cannot contain text children, so any childText is rejected by this sentinel guard.

Solutions

Remove text content from the animation element
Express values with Point3DKeyFrame children
Fix XAML whitespace issues (xml:space, line breaks creating text nodes)

Example fix

// before
<Point3DAnimationUsingKeyFrames>1,2,3</Point3DAnimationUsingKeyFrames>
// after
<Point3DAnimationUsingKeyFrames><LinearPoint3DKeyFrame KeyTime="0:0:1" Value="1,2,3"/></Point3DAnimationUsingKeyFrames>

Defensive patterns

Strategy: validation

Validate before calling

if (content is string) throw new InvalidOperationException("Timelines do not accept text children");

Prevention

Never put text nodes inside Point3DAnimationUsingKeyFrames
Use Point3DKeyFrame children for values
Check XAML for accidental text/whitespace content

When it happens

Trigger: Calling AddText(string) directly, or XAML text/whitespace inside <Point3DAnimationUsingKeyFrames>.

Common situations: Stray text nodes in XAML or misuse of IAddChild in custom parsers/designers.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/1a51d16733d29750. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Animation/Generated/Point3DAnimationUsingKeyFrames.cs:277

        /// WritePreamble() or WritePostscript().  It also doesn't throw an
        /// ArgumentNullException if the childText parameter is null.  These tasks
        /// are performed by the interface implementation.  Therefore, it's OK
        /// for a derived class to override this method and call the base
        /// class implementation only if they determine that it's the right
        /// course of action.  The derived class can rely on KeyFrameAnimation's
        /// implementation of IAddChild.AddChild or implement their own
        /// following the Freezable pattern since that would be a public
        /// method.
        /// </remarks>
        /// <param name="childText">A string representing the child text that
        /// should be added.  If this is a KeyFrameAnimation an exception will be
        /// thrown.</param>
        /// <exception cref="InvalidOperationException">Timelines have no way
        /// of adding text.</exception>
        [EditorBrowsable(EditorBrowsableState.Advanced)]
        protected virtual void AddText(string childText)
        {
            throw new InvalidOperationException(SR.Animation_NoTextChildren);
        }

        #endregion

        #region Point3DAnimationBase

        /// <summary>
        /// Calculates the value this animation believes should be the current value for the property.
        /// </summary>
        /// <param name="defaultOriginValue">
        /// This value is the suggested origin value provided to the animation
        /// to be used if the animation does not have its own concept of a
        /// start value. If this animation is the first in a composition chain
        /// this value will be the snapshot value if one is available or the
        /// base property value if it is not; otherise this value will be the 
        /// value returned by the previous animation in the chain with an 
        /// animationClock that is not Stopped.
        /// </param>

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