dotnet/maui · error · IndexOutOfRangeException

IItemsViewSource is empty

Error message

IItemsViewSource is empty

What it means

Thrown by EmptySource.GetItem(int) unconditionally. EmptySource is a sentinel IItemsViewSource representing an empty collection (Count == 0); calling GetItem on it is always invalid because there are no items. This throw indicates that the adapter or a caller failed to check Count before requesting an item, treating the empty sentinel as if it held data.

Source

Thrown at src/Compatibility/Core/src/Android/CollectionView/EmptySource.cs:44

				return false;
			}

			if (HasHeader)
			{
				return index == 1;
			}

			return index == 0;
		}

		public int GetPosition(object item)
		{
			return -1;
		}

		public object GetItem(int position)
		{
			throw new IndexOutOfRangeException("IItemsViewSource is empty");
		}
	}
}

View on GitHub (pinned to f377ff1c5e)

Solutions

1. Ensure ItemsSource is non-null and populated before issuing programmatic ScrollTo or Position commands.
2. Avoid calling ScrollTo(position) when the collection is known to be empty; guard with a count check.
3. Upgrade the Maui/Forms version; this throw often signals an internal bounds-check regression that gets patched.
4. If reproducing reliably, report it with the adapter call stack so the missing Count guard upstream can be fixed.

Example fix

// before
collectionView.ScrollTo(0, position: ScrollToPosition.Start); // may throw if source empty

// after
if (collectionView.ItemsSource is IList list && list.Count > 0)
    collectionView.ScrollTo(0, position: ScrollToPosition.Start);

// Guard ScrollTo/GetItem callers with a count check.
static bool HasItems(IItemsViewSource source) => source != null && source.Count > 0;
// Usage:
if (collectionView.ItemsSource is IList list && list.Count > 0)
    collectionView.ScrollTo(0);

try
{
    collectionView.ScrollTo(index);
}
catch (IndexOutOfRangeException ex) when (ex.Message.Contains("IItemsViewSource is empty"))
{
    // Source is empty; no-op or defer the scroll until data arrives.
    Log.Debug(nameof(CollectionView), "ScrollTo skipped; source is empty.");
}

When it happens

Trigger: A CollectionView or CarouselView is bound to a null or empty ItemsSource; the framework substitutes EmptySource. An internal code path (adapter, layout manager, or scroll helper) calls GetItem(0) without first verifying Count > 0. This is typically a framework-side bounds-check bug rather than a direct caller mistake.

Common situations: CollectionView/CarouselView with ItemsSource initially null, where a scroll-to or position operation races ahead of data binding. Framework version regressions where an adapter GetItem call lost its Count guard. Triggering a programmatic ScrollTo before the source is populated.

Related errors

• Can't set CarouselView to position {carouselPosition}. Items
• {nameof(element)} must be of type {typeof(IndicatorView).Nam
• {nameof(element)} must be of type {typeof(ItemsView).Name}
• Environment variable 'ANDROID_SDK_ROOT' or 'ANDROID_HOME' mu
• JAVA_HOME environment variable isn't set. Set it to your JDK

AI-assisted analysis of dotnet/maui@f377ff1c5e (2026-08-13). Data as JSON: /api/errors/2f1070482d9211a2. Report an issue: GitHub.