dotnet/wpf · error

SR.TableCollectionNotEnoughCapacity

Error message

SR.TableCollectionNotEnoughCapacity

What it means

The Capacity property setter throws ArgumentOutOfRangeException with SR.TableCollectionNotEnoughCapacity when the requested capacity is less than the current number of items (Size). Shrinking capacity below the live element count would orphan elements, so it is rejected.

Solutions

1. Clear the collection (or remove items) before setting a smaller Capacity
2. Set Capacity to a value >= collection.Size
3. Only shrink when Size == 0, or let the library's TrimToSize handle it

Example fix

// before
collection.Capacity = 0;
// after
if (collection.Size == 0) { collection.Capacity = 0; } else { collection.Clear(); collection.Capacity = 0; }

if (newCapacity >= collection.Size) collection.Capacity = newCapacity;

try { collection.Capacity = value; } catch (ArgumentOutOfRangeException) { /* clear items or choose a larger capacity */ }

When it happens

Trigger: Setting Capacity (or TrimToSize-like paths) to a value < Size, e.g. assigning 0 while the collection still contains items.

Common situations: Calling TrimToSize() on a non-empty collection where it maps to a capacity of Size but custom logic passes 0, or pre-sizing a fresh collection and later trying to shrink it without clearing first.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• SR.Format(SR.FrugalList_TargetMapCannotHoldAllData…
• SR.TableCollectionOutOfRange
• SR.VisualCollection_NotEnoughCapacity
• throw new ArgumentOutOfRangeException(nameof(index));
• args

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/423cc921aebeff67. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/MS/Internal/documents/ContentElementCollection.cs:757

        #region Internal Properties

        /// <summary>
        /// PrivateCapacity sets/gets the Capacity of the collection.
        /// </summary>
        internal int PrivateCapacity
        {
            get
            {
                return (Items.Length);
            }
            set
            {
                if (value != Items.Length)
                {
                    if (value < Size)
                    {
                        throw new ArgumentOutOfRangeException(SR.TableCollectionNotEnoughCapacity);
                    }

                    if (value > 0)
                    {
                        TItem[] newItems = new TItem[value];
                        if (Size > 0)
                        {
                            Array.Copy(Items, 0, newItems, 0, Size);
                        }
                        Items = newItems;
                    }
                    else
                    {
                        Items = new TItem[DefaultCapacity];
                    }
                }
            }
        }

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