dotnet/wpf · error · InvalidOperationException

Target element cannot receive focus.

Error message

Target element cannot receive focus.

What it means

ProxySimple.SetFocus (IRawElementProviderFragment) first tries the virtual SetFocus() override; if the proxy does not override it (or it cannot focus via HWND), the method throws InvalidOperationException with SR.SetFocusFailed — 'Target element cannot receive focus.' It means this proxy element type has no implemented focus mechanism.

Solutions

  1. Only call SetFocus on elements whose IsKeyboardFocusable property is true.
  2. Interact with the element through its supported patterns (Invoke, SelectionItem, Toggle) instead of focusing it.
  3. Focus a focusable ancestor/child (e.g. the owning window or an inner edit control) and then operate on the element.

Example fix

// before
labelProxy.SetFocus(); // InvalidOperationException: Target element cannot receive focus.

// after
var ae = (AutomationElement)labelProxy;
if (ae.Current.IsKeyboardFocusable)
{
    ae.SetFocus();
}
else
{
    // operate via patterns instead of focus
    var invoke = ae.GetCurrentPattern(InvokePattern.Pattern) as InvokePattern;
    invoke?.Invoke();
}
Defensive patterns

Strategy: validation

Validate before calling

static void EnsureFocusable(AutomationElement e)
{
    if (!e.Current.IsKeyboardFocusable)
        throw new InvalidOperationException($"{e.Current.AutomationId} is not keyboard focusable");
}

Type guard

static bool SupportsFocus(AutomationElement e) =>
    e.Current.IsKeyboardFocusable &&
    (e.Current.ControlType == ControlType.Button ||
     e.Current.ControlType == ControlType.Edit ||
     e.Current.ControlType == ControlType.Document ||
     e.Current.ControlType == ControlType.ListItem);

Try / catch

try { element.SetFocus(); }
catch (InvalidOperationException)
{
    // element cannot receive focus; drive it via patterns or focus a parent
    parentWindow.SetFocus();
}

Prevention

When it happens

Trigger: Calling SetFocus() on a UI Automation proxy element whose concrete proxy class does not override the virtual SetFocus() and is not keyboard-focusable (no HWND focus target), e.g. a static text or container proxy.

Common situations: Attempting to focus non-focusable controls (labels, panes) in legacy Win32/WinForms automation; using proxies for controls that don't expose WS_TABSTOP or a focusable HWND.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/f606945d19f5a953. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/UIAutomation/UIAutomationClientSideProviders/MS/Internal/AutomationProxies/ProxySimple.cs:552

            // a SetFocus() was called on them, the case to bool will cause a NullReferenceException.
            // So make sure the return is of type bool before casting.
            bool isKeyboardFocusable = true;
            object isKeyboardFocusableProperty = GetElementProperty(AutomationElement.IsKeyboardFocusableProperty);
            if (isKeyboardFocusableProperty is bool)
            {
                isKeyboardFocusable = (bool)isKeyboardFocusableProperty;
            }

            // UIAutomation already focuses the containing HWND for us, so only need to
            // set focus on the item within that...
            if (isKeyboardFocusable)
            {
                // Then set the focus on this item (virtual methods)
                SetFocus();
                return;
            }

            throw new InvalidOperationException(SR.SetFocusFailed);
        }

        #endregion

        //------------------------------------------------------
        //
        //  Internal Methods
        //
        //------------------------------------------------------

        #region Internal Methods

        // Returns the clickable point on the element
        // In the case when clickable point is obtained - method returns true
        // In the case when clickable point cannot be obtained - method returns false
        internal bool GetClickablePoint(out NativeMethods.Win32Point pt, bool fClipClientRect)
        {
            NativeMethods.Win32Rect rcItem = new NativeMethods.Win32Rect(BoundingRectangle);

View on GitHub (pinned to 81131a70a4)