dotnet/wpf · error · ArgumentException

SR.Format(SR.FrugalList_TargetMapCannotHoldAllData…

Error message

SR.Format(SR.FrugalList_TargetMapCannotHoldAllData, oldList.ToString(), this.ToString())

What it means

FrugalList Promote throws ArgumentException (message resource FrugalList_TargetMapCannotHoldAllData) when promoting a smaller-capacity frugal list into a larger one that is itself already full — the target map cannot hold all the data from the old list. This is an internal capacity invariant violation discovered during list promotion (called from Clone).

Solutions

  1. Promote to a capacity class at least large enough for oldList.Count plus existing target entries
  2. Ensure Promote is only called on targets with sufficient remaining capacity — check _count before promoting
  3. If hit through normal Add growth, this indicates an internal invariant bug; capture the list counts and file a WPF issue

Example fix

// before
if (oldList.Count > SIZE) Promote(oldList); // target too small
// after
if (Count + oldList.Count <= SIZE) Promote(oldList);
else Promote(new LargerList(this));
Defensive patterns

Strategy: try-catch

Validate before calling

if (target.Count + source.Count > target.Capacity) target = new LargerFrugalList(target);

Try / catch

try { target.Promote(oldList); }
catch (ArgumentException ex) when (ex.Message.Contains("CannotHoldAllData")) { /* promote to a larger capacity class instead */ }

Prevention

When it happens

Trigger: Clone (or Promote) is invoked to move a SingleItemList/ThreeItemList's contents into a larger frugal list whose current count plus the source count exceeds the target's fixed capacity — the target has no free slot for every old entry.

Common situations: Growth of frugal collections (used heavily by WPF dependency-property value stores) when many values are stored; a bug or corrupted count in the store can make the promotion target smaller than the source data.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/8e1a2f2230d4e066. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/Shared/MS/Utility/FrugalList.cs:331

            --_count;
        }

        public override T EntryAt(int index)
        {
            return _loneEntry;
        }

        public override void Promote(FrugalListBase<T> oldList)
        {
            if (oldList.Count == SIZE)
            {
                SetCount(SIZE);
                SetAt(0, oldList.EntryAt(0));
            }
            else
            {
                // this list is smaller than oldList
                throw new ArgumentException(SR.Format(SR.FrugalList_TargetMapCannotHoldAllData, oldList.ToString(), this.ToString()), nameof(oldList));
            }
        }

        // Class specific implementation to avoid virtual method calls and additional logic
        public void Promote(SingleItemList<T> oldList)
        {
            SetCount(oldList.Count);
            SetAt(0, oldList.EntryAt(0));
        }

        public override T[] ToArray()
        {
            T[] array = new T[SIZE];
            array[0] = _loneEntry;
            return array;
        }

        public override void CopyTo(T[] array, int index)

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