dotnet/wpf · error · InvalidOperationException

Storyboard_BeginStoryboardNameNotFound

Storyboard_BeginStoryboardNameNotFound

Error message

SR.Format(SR.Storyboard_BeginStoryboardNameNotFound, targetName)

What it means

The TargetName WAS found in the namescope, but the resolved object is not a BeginStoryboard. ControllableStoryboardActions must reference a BeginStoryboard by its x:Name; resolving to any other object (visual element, resource, the Storyboard itself) makes the control operation impossible, so an InvalidOperationException is thrown.

Solutions

Set the controlling action's TargetName to the x:Name of the BeginStoryboard element, not the Storyboard or a target element.
If defined in code, register the BeginStoryboard instance with FrameworkElement.RegisterName.
Rename conflicting names so the control TargetName is unambiguous.

Example fix

<!-- before: TargetName points at the Storyboard name -->
<BeginStoryboard x:Name="theBegin">
  <Storyboard x:Name="theStoryboard">...</Storyboard>
</BeginStoryboard>
<!-- PauseStoryboard TargetName="theStoryboard" -> throws -->

<!-- after -->
<!-- PauseStoryboard TargetName="theBegin" -->

Defensive patterns

Strategy: type-guard

Validate before calling

var resolved = fe.FindName(targetName);
if (resolved is not BeginStoryboard)
    throw new InvalidOperationException($"'{targetName}' resolves to {resolved?.GetType().Name}, not BeginStoryboard");

Type guard

resolved is BeginStoryboard beginStoryboard;

Try / catch

try { storyboard.Pause(fe); }
catch (InvalidOperationException ex) {
    // check TargetName points at the BeginStoryboard, not the Storyboard/element
}

Prevention

Point control-action TargetName only at BeginStoryboard x:Name.
Never reuse the Storyboard's x:Name as the control TargetName.
Rename on refactor to avoid name collisions.

When it happens

Trigger: TargetName of Pause/Resume/Stop/Seek/SkipToFill matches a registered name, but that name was registered for a different object — e.g. pointing at the Storyboard's own x:Name or at an animated element.

Common situations: Copy-paste mistakes pointing TargetName at the animated element; registering the Storyboard's x:Name and using it as the control TargetName; name collisions after refactoring.

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

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/3a5ea5c3d3f2410c. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Media/Animation/Storyboard.cs:350

        {
            namedObject = fce.FindName(targetName);
            if( namedObject == null )
            {
                throw new InvalidOperationException(
                    SR.Format(SR.Storyboard_NameNotFound, targetName, fce.GetType().ToString()));
            }
        }
        else
        {
            throw new InvalidOperationException(
                SR.Format(SR.Storyboard_NoNameScope, targetName));
        }

        beginStoryboard = namedObject as BeginStoryboard;

        if( beginStoryboard == null )
        {
            throw new InvalidOperationException(SR.Format(SR.Storyboard_BeginStoryboardNameNotFound, targetName));
        }

        return beginStoryboard;
    }

    /// <summary>
    ///     Recursively walks the clock tree and determine the target object
    /// and property for each clock in the tree.
    /// </summary>
    /// <remarks>
    ///     The currently active object and property path are passed in as parameters,
    /// they will be used unless a target/property specification exists on
    /// the Timeline object corresponding to the current clock.  (So that the
    /// leaf-most reference wins.)
    ///
    ///     The active object and property parameters may be null if they have
    /// never been specified.  If we reach a leaf node clock and a needed attribute
    /// is still null, it is an error condition.  Otherwise we keep hoping they'll be found.

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