dotnet/wpf · error · ArgumentOutOfRangeException

SR.TableCollectionCountNeedNonNegNum

Error message

SR.TableCollectionCountNeedNonNegNum

What it means

TableTextElementCollectionInternal<T>.RemoveRange rejects a negative count with ArgumentOutOfRangeException SR.TableCollectionCountNeedNonNegNum. The check happens after the index check, so index must already be in range; only a negative count triggers this particular error.

Solutions

  1. Validate/clamp the count first: count = Math.Max(0, count), and skip the call when it is zero.
  2. Fix the subtraction producing the count; compute it as Math.Max(0, end - start).
  3. For inverted ranges, normalize so start <= end before computing the count.
  4. Add a debug assertion on count >= 0 at the call site to catch regressions early.

Example fix

// before
collection.RemoveRange(start, end - start); // throws when end < start
// after
int count = Math.Max(0, end - start);
if (count > 0) collection.RemoveRange(start, count);
Defensive patterns

Strategy: validation

Validate before calling

int count = Math.Max(0, end - start);
if (count > 0 && start >= 0 && start < collection.Count)
    collection.RemoveRange(start, count);

Type guard

static bool IsValidRange(int start, int end) => end >= start && start >= 0;

Try / catch

try { collection.RemoveRange(index, count); }
count < 0 check: catch (ArgumentOutOfRangeException ex) when (count < 0) { count = 0; }

Prevention

When it happens

Trigger: RemoveRange(index, count) with count < 0 — typically from a subtraction like end - start where end < start, or an uninitialized/default variable.

Common situations: Range bookkeeping where the end was captured before the start was updated, selection-range math on inverted selections, and refactored code that swapped parameter order.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/dc176c751a2d83d2. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/MS/Internal/documents/TableTextElementCollectionInternal.cs:225

        /// <exception cref="ArgumentException">
        /// <c>index</c> and <c>count</c> do not denote a valid range of TItems in the ContentElementCollection.
        /// </exception>
        /// <remarks>
        /// The TItems that follow the removed TItems move up to occupy
        /// the vacated spot. The indices of the TItems that are moved are
        /// also updated.
        /// </remarks>
        public override void RemoveRange(int index, int count)
        {
            Version++;

            if (index < 0 || index >= Size)
            {
                throw new ArgumentOutOfRangeException(SR.TableCollectionOutOfRange);
            }
            if (count < 0)
            {
                throw new ArgumentOutOfRangeException(SR.TableCollectionCountNeedNonNegNum);
            }
            if (Size - index < count)
            {
                throw new ArgumentException(SR.TableCollectionRangeOutOfRange);
            }

            if (count > 0)
            {
                for (int i = index + count - 1; i >= index; --i)
                {
                    Debug.Assert(BelongsToOwner(Items[i]));
                    Remove(Items[i]);
                }
            }
}

        /// <summary>
        /// Sets the specified TItem at the specified index;

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