dotnet/wpf · error · InvalidOperationException

SR.ItemCollectionHasNoCollection

Error message

SR.ItemCollectionHasNoCollection

What it means

ItemCollection.GetItemAt throws InvalidOperationException(SR.ItemCollectionHasNoCollection) when ItemsSource has not been set (or the binding produced no collection) and no items were added directly, so the ItemCollection has no underlying collection view to index into. Without a view there is no item at any index.

Solutions

  1. Set ItemsSource to a non-null collection before calling GetItemAt.
  2. Check items.Count > 0 (or IsUsingItemsSource / EnsureCollectionView state) before indexing.
  3. If relying on a binding, defer the call until DataContext is available (e.g. Loaded event) and verify the binding produced a value.

Example fix

// before
var item = listBox.Items.GetItemAt(0);
// after
if (listBox.Items.Count > 0)
    var item = listBox.Items.GetItemAt(0);
Defensive patterns

Strategy: validation

Validate before calling

if (itemsControl.ItemsSource != null && itemsControl.Items.Count > index)
    var item = itemsControl.Items.GetItemAt(index);

Type guard

static bool HasItems(ItemCollection c) => c != null && c.Count > 0;

Try / catch

try { var item = items.GetItemAt(i); }
catch (InvalidOperationException) { item = null; /* no collection bound */ }

Prevention

When it happens

Trigger: Calling GetItemAt(index) on an ItemsControl whose ItemsSource binding returned null or was never assigned, and which has no direct items added via Items.Add.

Common situations: Accessing listbox.Items.GetItemAt(...) before DataContext/binding resolves; binding to a property that initially returns null; calling in a constructor before the template/binding engine has supplied the source.

Understand the failure class

Background: EmptyResultError / "no results found": when an API or scraper succeeds but returns zero rows — this error's family across 9 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/83a4d77220b42f2b. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/ItemCollection.cs:335

        /// <summary>
        /// Retrieve item at the given zero-based index in this CollectionView.
        /// </summary>
        /// <remarks>
        /// <p>The index is evaluated with any SortDescriptions or Filter being set on this CollectionView.</p>
        /// </remarks>
        /// <exception cref="ArgumentOutOfRangeException">
        /// Thrown if index is out of range
        /// </exception>
        public override object GetItemAt(int index)
        {
            // only check lower bound because Count could be expensive
            ArgumentOutOfRangeException.ThrowIfNegative(index);

            VerifyRefreshNotDeferred();

            if (!EnsureCollectionView())
                throw new InvalidOperationException(SR.ItemCollectionHasNoCollection);

            if (_collectionView == _internalView)
            {
                // check upper bound here because we know it's not expensive
                ArgumentOutOfRangeException.ThrowIfGreaterThanOrEqual(index, _internalView.Count);
            }

            return _collectionView.GetItemAt(index);
        }



        /// <summary>
        ///     Insert an item in the collection at a given index.  All items
        /// after the given position are moved down by one.
        /// </summary>
        /// <param name="insertIndex">
        ///     The index at which to inser the item

View on GitHub (pinned to 81131a70a4)