dotnet/wpf · error · InvalidOperationException

SR.DoesNotSupportMultipleSelection

Error message

SR.DoesNotSupportMultipleSelection

What it means

WindowsTab's ISelectionItemProvider.Select throws InvalidOperationException with resource SR.DoesNotSupportMultipleSelection when code reaches a branch that permits multi-selection but the tab control only allows a single selection. The UIA Selection pattern contract requires the provider to reject a Select call that would create multiple selections on a control that does not support it. The proxy enforces the single-selection invariant of the Win32 tab control.

Solutions

1. Do not call Select on a second tab while another is selected; call Select only on the desired tab item - the single-select control deselects the rest
2. Check SelectionPattern.CanSelectMultiple on the parent tab before issuing multi-select-style calls
3. Catch InvalidOperationException and treat it as 'operation unsupported for this control'
4. Recreate the automation sequence to model single selection instead of additive selection

Example fix

// before
foreach (var tab in tabItems) tab.Select(); // additive multi-select
// after
foreach (var tab in tabItems) { if (!tab.Current.IsSelected) tab.Select(); } // ensures single selection

bool canAdditiveSelect = selectionPattern.Current.CanSelectMultiple; if (!canAdditiveSelect) throw new SkipSelectionException();

bool IsMultiSelectable(AutomationElement el) => el.TryGetCurrentPattern(SelectionPattern.Pattern, out var p) && ((SelectionPattern)p).Current.CanSelectMultiple;

When it happens

Trigger: Calling UIA SelectionItemPattern.Select() on a tab item of a Win32 tab control whose code path enters the multi-selection branch while the control allows only one selected item (e.g. TCS_MULTISELECT-style handling where only single selection is actually permitted).

Common situations: Automation scripts selecting tab items on classic Win32 tab controls; apps whose tab style changed between frameworks; UIA clients assuming Excel-like multi-select tabs.

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

• E_ACCESSDENIED
• E_INVALIDARG
• E_OUTOFMEMORY
• E_UNEXPECTED
• ElementNotAvailableException

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/72f0bb3b87473bf7. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/UIAutomation/UIAutomationClientSideProviders/MS/Internal/AutomationProxies/WindowsTab.cs:1113

            // If multiple selections allowed, add requested selection
            if (WindowsTab.SupportMultipleSelection(_hwnd))
            {
                // Press ctrl and mouse click tab
                NativeMethods.Win32Point pt = new NativeMethods.Win32Point();
                if (GetClickablePoint(out pt, true))
                {
                    Input.SendKeyboardInput(Key.LeftCtrl, true);
                    Misc.MouseClick(pt.x, pt.y);
                    Input.SendKeyboardInput(Key.LeftCtrl, false);
                    return;
                }

                throw new InvalidOperationException(SR.OperationCannotBePerformed);
            }
            // else only single selection allowed
            else
            {
                throw new InvalidOperationException(SR.DoesNotSupportMultipleSelection);
            }
        }

        // Removes this element from the selection
        void ISelectionItemProvider.RemoveFromSelection()
        {
            // Make sure that the control is enabled
            if (!SafeNativeMethods.IsWindowEnabled(_hwnd))
            {
                throw new ElementNotEnabledException();
            }

            // If not selected, done
            if (!((ISelectionItemProvider)this).IsSelected)
            {
                return;
            }

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