dotnet/wpf · error · InvalidOperationException

SR.Format(SR.Invalid_IInputElement…

Error message

SR.Format(SR.Invalid_IInputElement, _stylusCapture.GetType())

What it means

WispLogic capture-apply path subscribes IsEnabled/IsVisible/IsHitTestVisible change handlers to the new _stylusCapture. When the capture target is neither UIElement, ContentElement, nor UIElement3D, no handler wiring is possible, so it throws InvalidOperationException naming the type. This mirrors error 697 but fires when establishing capture rather than releasing it.

Solutions

Derive the capture target from UIElement (or ContentElement/UIElement3D)
Capture the nearest supported ancestor instead of the visual itself
Add a guard with InputElement.IsValid(element) before calling Capture

Example fix

// before
Stylus.Capture(drawingVisual, CaptureMode.Element);
// after
if (InputElement.IsValid(drawingVisual))
    Stylus.Capture(drawingVisual, CaptureMode.Element);
else
    Stylus.Capture(FindAncestor<UIElement>(drawingVisual), CaptureMode.Element);

Defensive patterns

Strategy: type-guard

Validate before calling

if (InputElement.IsValid(element))
    Stylus.Capture(element, CaptureMode.Element);

Type guard

bool CanCapture(IInputElement e) => e is UIElement || e is ContentElement || e is UIElement3D;

Try / catch

try { Stylus.Capture(element, CaptureMode.Element); }
catch (InvalidOperationException ex) { Log.Warn("Invalid stylus capture element", ex); }

Prevention

Always derive capture targets from UIElement
Wrap DrawingVisual content in a UIElement host before capture
Use InputElement.IsValid as a pre-capture gate

When it happens

Trigger: Calling Stylus.Capture(element, ...) or StylusDevice.Capture with an element that is a DependencyObject but not one of the three supported input element types; the throw happens while wiring change notifications in WispLogic.

Common situations: Capturing a DrawingVisual or custom IInputElement; interop code capturing on non-element visuals; unit-test fakes passed to Stylus.Capture.

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/a50b84a7e75f971c. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Stylus/Wisp/WispLogic.cs:2116

                    }
                    else if (o is ContentElement ce)
                    {
                        ce.IsEnabledChanged += _captureIsEnabledChangedEventHandler;

                        // NOTE: there are no IsVisible or IsHitTestVisible properties for ContentElements.
                        //
                        // ce.IsVisibleChanged += _captureIsVisibleChangedEventHandler;
                        // ce.IsHitTestVisibleChanged += _captureIsHitTestVisibleChangedEventHandler;
                    }
                    else if (o is UIElement3D uie3D)
                    {
                        uie3D.IsEnabledChanged += _captureIsEnabledChangedEventHandler;
                        uie3D.IsVisibleChanged += _captureIsVisibleChangedEventHandler;
                        uie3D.IsHitTestVisibleChanged += _captureIsHitTestVisibleChangedEventHandler;
                    }
                    else
                    {
                        throw new InvalidOperationException(SR.Format(SR.Invalid_IInputElement, _stylusCapture.GetType())); 
                    }
                }

                // Oddly enough, update the IsStylusCaptureWithin property first.  This is
                // so any callbacks will see the more-common IsStylusCaptureWithin property
                // set correctly.
                UIElement.StylusCaptureWithinProperty.OnOriginValueChanged(oldCapture as DependencyObject, _stylusCapture as DependencyObject, ref _stylusCaptureWithinTreeState);

                // Invalidate the IsStylusCaptured properties.
                if (oldCapture != null)
                {
                    o = oldCapture as DependencyObject;
                    o.SetValue(UIElement.IsStylusCapturedPropertyKey, false); // Same property for ContentElements
                }
                if (_stylusCapture != null)
                {
                    o = _stylusCapture as DependencyObject;
                    o.SetValue(UIElement.IsStylusCapturedPropertyKey, true); // Same property for ContentElements

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