dotnet/wpf · error · ArgumentException

SR.PropertyNotSupported

Error message

SR.PropertyNotSupported

What it means

DataGridColumnHeadersPresenterAutomationPeer.GetChildrenCore calls IsPropertySupportedByControlForFindItem(propertyId) for property-scoped find requests; if the requested automation property is not supported by this control, it throws ArgumentException with SR.PropertyNotSupported to signal the property id is invalid for find-item queries. (The method also resets its children cache before rebuilding the header peers.)

Solutions

  1. Remove unsupported properties from the UIA FindItem/FindFirst property condition and search only with supported ids.
  2. Catch ArgumentException from find calls and retry without the property condition.
  3. Use property id 0 or supported properties (e.g. AutomationId, Name) when searching header children.
  4. Verify which properties the control supports before building search conditions.

Example fix

// before
var cond = new PropertyCondition(ValuePattern.ValueProperty, "x"); // unsupported for find
var header = presenterPeer.FindFirst(TreeScope.Children, cond);

// after
var cond = new PropertyCondition(AutomationElement.NameProperty, "Name");
var header = presenterPeer.FindFirst(TreeScope.Children, cond);
Defensive patterns

Strategy: try-catch

Validate before calling

// Build find conditions only from properties the control supports (e.g. AutomationId, Name).

Try / catch

try { peer.FindFirst(TreeScope.Children, condition); } catch (ArgumentException) { /* retry with supported/empty property condition */ }

Prevention

When it happens

Trigger: A UI Automation client performs a FindFirst/FindAll with a property condition using a propertyId that the DataGridColumnHeadersPresenter control does not support (IsPropertySupportedByControlForFindItem returns false), while propertyId != 0; the provider layer then surfaces this ArgumentException.

Common situations: UIA search conditions referencing properties unavailable on headers presenter (e.g. value/selection properties); custom automation clients probing unsupported properties; property ids changed or misused across framework versions.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/52bf40c074b3eae0. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Automation/Peers/DataGridColumnHeadersPresenterAutomationPeer.cs:158

        ///<summary>
        /// Find Childrend Peers based on Automation Properties.
        /// Used to enable virtualization with automation.
        ///
        /// GetChildrenCore and FindItemByProperty are almost straight copies of the
        /// ItemControlAutomationPeer code; however since DataGridColumHeaderPresenter
        /// returns the Column.Header's as the items some specialized code was needed to
        /// create and store peers.
        ///</summary>
        IRawElementProviderSimple IItemContainerProvider.FindItemByProperty(IRawElementProviderSimple startAfter, int propertyId, object value)
        {
            ResetChildrenCache();
            // Checks if propertyId is valid else throws ArgumentException to notify it as invalid argument is being passed
            if (propertyId != 0)
            {
                if (!IsPropertySupportedByControlForFindItem(propertyId))
                {
                    throw new ArgumentException(SR.PropertyNotSupported);
                }
            }

            ItemsControl owner = (ItemsControl)Owner;

            IList items = null;
            if (owner != null)
                items = OwningDataGrid.Columns;

            if (items != null && items.Count > 0)
            {
                DataGridColumnHeaderItemAutomationPeer startAfterItem = null;
                if (startAfter != null)
                {
                    // get the peer corresponding to this provider
                    startAfterItem = PeerFromProvider(startAfter) as DataGridColumnHeaderItemAutomationPeer;
                    if (startAfterItem == null)
                        return null;

View on GitHub (pinned to 81131a70a4)