dotnet/wpf · error · ElementNotAvailableException

Microsoft.Windows.Controls.SR.VirtualizedElement

Error message

Microsoft.Windows.Controls.SR.VirtualizedElement

What it means

IExpandCollapseProvider.Collapse on RibbonMenuItemDataAutomationPeer mirrors Expand: if GetWrapper() returns null the RibbonMenuItem container is not realized (virtualized or submenu closed), and the peer throws ElementNotAvailableException with SR.VirtualizedElement.

Solutions

Verify the element is available (e.g. via AutomationElement.GetCurrentPropertyValue or TryGetPattern) and realize it by opening the parent menu before Collapse.
Walk the live UIA tree and only collapse elements that currently exist in the tree.
Catch ElementNotAvailableException around Collapse and skip/refresh stale peer references.
Re-acquire the AutomationElement from the UIA tree instead of caching peers across virtualization changes.

Example fix

// before
cachedExpandCollapsePattern.Collapse();
// after
try { cachedExpandCollapsePattern.Collapse(); }
catch (ElementNotAvailableException) { cachedElement = reFindElement(); }

Defensive patterns

Strategy: try-catch

Validate before calling

if (element != null && !element.IsOffscreen) collapse();

Type guard

if (peer.GetWrapper() is RibbonMenuItem) { /* element realized */ }

Try / catch

try { expandCollapsePattern.Collapse(); }
catch (ElementNotAvailableException) { /* element virtualized; skip or re-find */ }

Prevention

Collapse elements that are currently live in the UIA tree only
Re-acquire AutomationElements after any menu open/close
Avoid iterating cached peers across virtualization events

When it happens

Trigger: Calling Collapse() on a RibbonMenuItemDataAutomationPeer whose wrapper UIElement is null because the item's container was never realized or was recycled by virtualization.

Common situations: Automation scripts collapsing all open submenus by iterating peers, where some items have no realized containers; containers discarded after the submenu was closed programmatically.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/76f5e80dde203860. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/System.Windows.Controls.Ribbon/Microsoft/Windows/Automation/Peers/RibbonMenuItemDataAutomationPeer.cs:171

                menuItemOwner.IsSubmenuOpen = true;
            }
            else
            {
                throw new InvalidOperationException(Microsoft.Windows.Controls.SR.UIA_OperationCannotBePerformed);
            }
        }

        ///
        void IExpandCollapseProvider.Collapse()
        {
            if (!IsEnabled())
                throw new ElementNotEnabledException();

            UIElement owner = GetWrapper();
            if (owner == null)
            {
                throw new ElementNotAvailableException(Microsoft.Windows.Controls.SR.VirtualizedElement);
            }

            RibbonMenuItem menuItemOwner = owner as RibbonMenuItem;
            if (menuItemOwner != null)
            {
                MenuItemRole role = menuItemOwner.Role;

                if ((role != MenuItemRole.TopLevelHeader && role != MenuItemRole.SubmenuHeader)
                    || !menuItemOwner.HasItems)
                {
                    throw new InvalidOperationException(Microsoft.Windows.Controls.SR.UIA_OperationCannotBePerformed);
                }

                menuItemOwner.IsSubmenuOpen = false;
            }
            else
            {
                throw new InvalidOperationException(Microsoft.Windows.Controls.SR.UIA_OperationCannotBePerformed);

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