stride3d/stride · error · NotSupportedException

is not a supported mode.

Error message

 is not a supported mode.

What it means

SortedList's internal enumerators use an EnumeratorMode (KEY_MODE/VALUE_MODE/ENTRY_MODE). Reading Current falls through to a default case that throws NotSupportedException when the mode is none of the known values. This is effectively an internal invariant violation: user code should never be able to set the mode directly.

Solutions

1. Stop capturing/serializing enumerator objects; create a fresh enumerator via GetEnumerator() each time you iterate
2. Verify no reflection or derived-class code writes to the enumerator's mode field
3. Iterate with foreach or an explicitly typed interface (IDictionaryEnumerator/IEnumerator) so the correct mode is set by the library

Example fix

// before
var e = ((IEnumerable)sortedList).GetEnumerator();
Serialize(e); // corrupts internal mode
// after
foreach (DictionaryEntry entry in sortedList) { /* use entry */ }

bool isEnumeratorValid(IEnumerator e) => e != null && (e.GetType().Name != "SortedListEnumerator" || IsKnownMode(e));

try { var cur = enumerator.Current; } catch (NotSupportedException) { enumerator = sortedList.GetEnumerator(); }

When it happens

Trigger: Reading Current from a SortedList enumerator whose _mode field holds a value outside KEY_MODE/VALUE_MODE/ENTRY_MODE — typically only via reflection, serialization of the enumerator, or memory/state corruption.

Common situations: Debugging tools or tests poking at enumerator internals; deserializing a captured enumerator object; custom derived code that assigned an invalid mode.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Collection was modified after the enumerator was…
• attempt to modify a key
• This operation is not supported by the source tracker.
• InvalidOperationException
• The collection was modified after the enumerator was…

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/b6e3c4a073313109. Report an issue: GitHub.

Appendix: source

Thrown at sources/core/Stride.Core/Collections/SortedList.cs:785

        public object Current
        {
            get
            {
                if (invalid || pos >= size || pos == -1)
                    throw new InvalidOperationException(xstr);

                switch (mode)
                {
                    case EnumeratorMode.KEY_MODE:
                        return currentKey;
                    case EnumeratorMode.VALUE_MODE:
                        return currentValue;
                    case EnumeratorMode.ENTRY_MODE:
                        return this.Entry;

                    default:
                        throw new NotSupportedException(mode + " is not a supported mode.");
                }
            }
        }

        // ICloneable

        public object Clone()
        {
            var e = new DictionaryEnumerator(host, mode);
            e.stamp = stamp;
            e.pos = pos;
            e.size = size;
            e.currentKey = currentKey;
            e.currentValue = currentValue;
            e.invalid = invalid;
            return e;
        }
    }

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