stride3d/stride · warning · InvalidOperationException

Internal error, the collection has already muted to a…

Error message

Internal error, the collection has already muted to a dictionary.

What it means

The private ChangeOver method converts the internal list storage to a Dictionary; it throws InvalidOperationException if the transition already happened (list is null). This is an internal invariant guard — user code should never trigger it directly; hitting it indicates a bug or misuse via reflection.

Solutions

1. Report as a bug if hit through normal public API usage
2. Avoid concurrent mutation of the HybridDictionary from multiple threads without synchronization
3. Do not call private members via reflection

try { collection.Add(kvp); }
catch (InvalidOperationException) { /* internal invariant bug — report */ }

When it happens

Trigger: Only reachable if ChangeOver is invoked after the collection already cut over to dictionary mode — an internal invariant violation, not a normal usage error.

Common situations: Practically never hit by library users; would indicate corrupted internal state, a race between threads mutating the collection, or reflection-based misuse.

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

• Two elements of the collection have the same id
• An id is both marked as deleted and associated to a key of…
• This operation is not supported by the source tracker.
• An item with the same key has already been added.
• The given key was not present in the dictionary.

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/93e42d6482fb3de9. Report an issue: GitHub.

Appendix: source

Thrown at sources/core/Stride.Core.Design/Collections/HybridDictionary.cs:339

        if (list != null)
        {
            if (list.Count + 1 < CutoverPoint)
            {
                list.Add(item);
                return;
            }
            else
            {
                ChangeOver();
            }
        }
        dictionary!.Add(item.Key, item.Value);
    }

    private void ChangeOver()
    {
        if (list == null)
            throw new InvalidOperationException("Internal error, the collection has already muted to a dictionary.");

        dictionary = new Dictionary<TKey, TValue>(InitialDictionarySize, keyComparer);
        foreach (var item in list)
        {
            dictionary.Add(item.Key, item.Value);
        }
        list = null;
    }
}

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