dotnet/wpf · error · ArgumentException

SR.EmptyArrayNotAllowedAsArgument

Error message

SR.EmptyArrayNotAllowedAsArgument

What it means

IncrementalHitTester.AddPoints(IEnumerable<Point>) rejects empty enumerations with ArgumentException (SR.EmptyArrayNotAllowedAsArgument) because hit-testing requires at least one point. It also throws InvalidOperationException if EndHitTesting was already called (error 508).

Solutions

1. Check points has at least 1 point before calling AddPoints
2. Skip hit-testing entirely for empty point sets

Example fix

// before
hitTester.AddPoints(points);
// after
if (points != null && points.Any()) hitTester.AddPoints(points);

if (points == null || !points.Any()) return;

static bool HasPoints(IEnumerable<Point> p) => p != null && p.Any();

try { tester.AddPoints(points); } catch (ArgumentException) { /* empty point set — nothing to hit-test */ } catch (InvalidOperationException) { /* EndHitTesting already called */ }

When it happens

Trigger: Calling AddPoints with an empty Point collection/array; calling via AddPoint delegation with an empty source.

Common situations: Hit-testing against a stroke whose collected point list is empty (stroke captured with no samples); passing a filtered point set where the filter removed everything.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• ExtendedProperty is already part of the…
• GUID cannot be empty.
• InvalidMatrixContainsInfinity
• InvalidMatrixContainsNaN
• InvalidValueOfType

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/8b7dc07753965d59. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Ink/IncrementalHitTester.cs:41

        /// Adds a point representing an incremental move of the hit-testing tool
        /// </summary>
        /// <param name="point">a point that represents an incremental move of the hitting tool</param>
        public void AddPoint(Point point)
        {
            AddPoints(new Point[1] { point });
        }

        /// <summary>
        /// Adds an array of points representing an incremental move of the hit-testing tool
        /// </summary>
        /// <param name="points">points representing an incremental move of the hitting tool</param>
        public void AddPoints(IEnumerable<Point> points)
        {
            ArgumentNullException.ThrowIfNull(points);

            if (IEnumerablePointHelper.GetCount(points) == 0)
            {
                throw new System.ArgumentException(SR.EmptyArrayNotAllowedAsArgument, nameof(points));
            }

            if (!_fValid)
            {
                throw new System.InvalidOperationException(SR.EndHitTestingCalled);
            }

            System.Diagnostics.Debug.Assert(_strokes != null);

            AddPointsCore(points);
        }

        /// <summary>
        /// Adds a StylusPacket representing an incremental move of the hit-testing tool
        /// </summary>
        /// <param name="stylusPoints">stylusPoints</param>
        public void AddPoints(StylusPointCollection stylusPoints)
        {

View on GitHub (pinned to 81131a70a4)