AvaloniaUI/Avalonia · error · InvalidOperationException

Invalid Arrange rectangle.

Error message

Invalid Arrange rectangle.

What it means

Arrange throws when the supplied Rect has a negative or non-finite Width/Height, or a non-finite X/Y. Layout positions and sizes must be finite and non-negative in size; an invalid arrange rectangle would place the control at an uncomputable position or give it an impossible area. Note X/Y may be any finite value (including negative offset) but Width/Height must be >= 0 and finite.

Source

Thrown at src/Avalonia.Base/Layout/Layoutable.cs:419

                Logger.TryGet(LogEventLevel.Verbose, LogArea.Layout)?.Log(this, "Measure requested {DesiredSize}", DesiredSize);

                if (DesiredSize != previousDesiredSize)
                {
                    this.GetVisualParent<Layoutable>()?.ChildDesiredSizeChanged(this);
                }
            }
        }

        /// <summary>
        /// Arranges the control and its children.
        /// </summary>
        /// <param name="rect">The control's new bounds.</param>
        public void Arrange(Rect rect)
        {
            if (IsInvalidRect(rect))
            {
                throw new InvalidOperationException("Invalid Arrange rectangle.");
            }

            if (!IsMeasureValid)
            {
                Measure(_previousMeasure ?? rect.Size);
            }

            if (!IsArrangeValid || _previousArrange != rect)
            {
                using var activity = Diagnostic.ArrangingLayoutable()?
                    .AddTag(Diagnostic.Tags.Control, this);

                Logger.TryGet(LogEventLevel.Verbose, LogArea.Layout)?.Log(this, "Arrange to {Rect} ", rect);

                IsArrangeValid = true;
                ArrangeCore(rect);
                _previousArrange = rect;
            }

View on GitHub (pinned to 11c5427268)

Solutions

1. Clamp width and height to >= 0 and ensure all components are finite before calling Arrange.
2. Verify the arrange rect is within sensible bounds in ArrangeOverride: use new Rect(x, y, Math.Max(0, w), Math.Max(0, h)).
3. Check upstream measure results feeding into arrange math.

Example fix

// before
var rect = new Rect(x, y, available.Width - childWidth, available.Height);
child.Arrange(rect);

// after
var w = Math.Max(0, available.Width - childWidth);
var h = Math.Max(0, available.Height);
child.Arrange(new Rect(x, y, w, h));

static Rect ValidArrange(Rect r) => new Rect(r.X, r.Y,
    Math.Max(0, r.Width), Math.Max(0, r.Height));

child.Arrange(ValidArrange(rect));

When it happens

Trigger: Calling control.Arrange(rect) where rect.Width or rect.Height is negative, NaN, or Infinity, or where rect.X/rect.Y is NaN or Infinity. Common in custom panels computing final rects from measure results that went bad.

Common situations: Custom panel ArrangeOverride computing a rect with negative width (e.g. child.DesiredSize.Width minus something larger). Passing a rect built from an unset/uninitialized point. Arithmetic overflow or division producing Infinity.

Related errors

• Cannot call Measure using a size with NaN values.
• 'MaxTextHeight' property value cannot be NaN.
• The control isn't currently attached to a toplevel
• Invalid render scaling value {scaling}
• Attempt to call InvalidateMeasure on wrong LayoutManager.

AI-assisted analysis of AvaloniaUI/Avalonia@11c5427268 (2026-08-13). Data as JSON: /api/errors/5532700657e22451. Report an issue: GitHub.