stride3d/stride · error · ArgumentNullException

arrayIndex is greater than or equal to array.Length

Error message

arrayIndex is greater than or equal to array.Length

What it means

CopyTo on Stride's SortedList throws when the caller-supplied starting index (arrayIndex) is greater than or equal to the destination array's Length, meaning there is no room to write even one element. The library uses an argument-validation guard before iterating elements. Note the code mistakenly throws ArgumentNullException with a descriptive message; the type is misleading but the condition is an ArgumentOutOfRange/Index scenario.

Solutions

1. Ensure array.Length is greater than arrayIndex before calling CopyTo.
2. Size the destination array to at least sortedList.Count plus the offset: new KeyValuePair<TKey,TValue>[list.Count + arrayIndex].
3. If copying from index 0, just use new KeyValuePair<TKey,TValue>[list.Count].

Example fix

// before
var pairs = new KeyValuePair<string,int>[0];
sortedList.CopyTo(pairs, 0);
// after
var pairs = new KeyValuePair<string,int>[sortedList.Count];
sortedList.CopyTo(pairs, 0);

if (array == null) throw new ArgumentNullException(nameof(array));
if (arrayIndex < 0 || arrayIndex >= array.Length)
    throw new ArgumentOutOfRangeException(nameof(arrayIndex));
if (sortedList.Count > array.Length - arrayIndex)
    throw new ArgumentException("Destination array too small.");

static bool CanCopyTo<T>(KeyValuePair<TKey,TValue>[] array, int index, int count) =>
    array != null && index >= 0 && index < array.Length && count <= array.Length - index;

try { sortedList.CopyTo(array, arrayIndex); }
catch (ArgumentNullException ex) when (ex.Message.Contains("arrayIndex")) { /* resize and retry */ }

When it happens

Trigger: Calling CopyTo(array, arrayIndex) where arrayIndex >= array.Length, e.g. CopyTo(new KeyValuePair<K,V>[0], 0) or CopyTo(arr, arr.Length).

Common situations: Copying into a zero-length or undersized buffer, computing the offset from a wrong cursor/offset variable, or passing an array sized for a different collection.

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

• Capacity must be greater than 0.
• Capacity must be a power of two
• Not enough space in array from arrayIndex to end of array
• array is multi-dimensional
• No Collection item identifier associated to the given collec

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/89c640f77dd43c65. Report an issue: GitHub.

Appendix: source

Thrown at sources/core/Stride.Core/Collections/SortedList.cs:276

    {
        defaultCapacity = INITIAL_SIZE;
        this.table = new KeyValuePair<TKey, TValue>[defaultCapacity];
        inUse = 0;
        modificationCount++;
    }

    void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
    {
        if (Count == 0)
            return;

        ArgumentNullException.ThrowIfNull(array);

        if (arrayIndex < 0)
            throw new ArgumentOutOfRangeException();

        if (arrayIndex >= array.Length)
            throw new ArgumentNullException("arrayIndex is greater than or equal to array.Length");
        if (Count > (array.Length - arrayIndex))
            throw new ArgumentNullException("Not enough space in array from arrayIndex to end of array");

        var i = arrayIndex;
        foreach (var pair in this)
            array[i++] = pair;
    }

    void ICollection<KeyValuePair<TKey, TValue>>.Add(KeyValuePair<TKey, TValue> keyValuePair)
    {
        Add(keyValuePair.Key, keyValuePair.Value);
    }

    bool ICollection<KeyValuePair<TKey, TValue>>.Contains(KeyValuePair<TKey, TValue> keyValuePair)
    {
        var i = Find(keyValuePair.Key);

        if (i >= 0)

View on GitHub (pinned to 96fad776d2)