Unity-Technologies/UnityCsReference · error · ArgumentOutOfRangeException

columnIndex {0} is not valid when the current column count i

Error message

columnIndex {0} is not valid when the current column count is {1}

What it means

Thrown by MultiColumnHeader.GetColumn when columnIndex is negative or >= state.columns.Length. Every column accessor validates bounds because the columns array is the source of truth for width, sorting, and header content.

Source

Thrown at Editor/Mono/GUI/TreeView/MultiColumnHeader.cs:146

        public void SetSortDirection(int columnIndex, bool sortAscending)
        {
            var column = GetColumn(columnIndex);
            if (column.sortedAscending != sortAscending)
            {
                column.sortedAscending = sortAscending;
                OnSortingChanged();
            }
        }

        public bool IsSortedAscending(int columnIndex)
        {
            return GetColumn(columnIndex).sortedAscending;
        }

        public MultiColumnHeaderState.Column GetColumn(int columnIndex)
        {
            if (columnIndex < 0 || columnIndex >= state.columns.Length)
                throw new ArgumentOutOfRangeException("columnIndex", string.Format("columnIndex {0} is not valid when the current column count is {1}", columnIndex, state.columns.Length));
            return state.columns[columnIndex];
        }

        public bool IsColumnVisible(int columnIndex)
        {
            foreach (int vc in state.visibleColumns)
            {
                if (vc == columnIndex)
                    return true;
            }
            return false;
        }

        public int GetVisibleColumnIndex(int columnIndex)
        {
            for (int i = 0; i < state.visibleColumns.Length; i++)
            {
                if (state.visibleColumns[i] == columnIndex)

View on GitHub (pinned to 225b0fbdb5)

Solutions

1. Bounds-check columnIndex against state.columns.Length before calling.
2. Clamp or ignore out-of-range indices when restoring saved state.
3. Use IsColumnVisible / GetVisibleColumnIndex to translate between the two index spaces correctly.

Example fix

// before
var col = header.GetColumn(idx);

// after
if (idx >= 0 && idx < header.state.columns.Length)
    var col = header.GetColumn(idx);
else return; // invalid index, skip

if (columnIndex < 0 || columnIndex >= header.state.columns.Length) return default;

static bool IsValidColumnIndex(int i, MultiColumnHeader h) => i >= 0 && i < h.state.columns.Length;

When it happens

Trigger: Requesting a column by an index that doesn't exist; using a visible-column index where a full column index is expected.

Common situations: Columns were removed but a stale index was persisted; confusing visible column indices with absolute column indices.

Related errors

• The provided visibleColumnIndex is invalid. Ensure the index
• MultiColumnHeader state is not allowed to be null
• columnIndices
• sortAscending
• Input arrays should have same length

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/c136f96776940efc. Report an issue: GitHub.