Unity-Technologies/UnityCsReference · error · ArgumentException

Invalid search: cannot be null or empty

Error message

Invalid search: cannot be null or empty

What it means

Thrown by TreeViewControlDataSource.SearchFullTree when the search string is null or empty. The method walks the tree pushing items onto a stack and filtering by the search term; an empty/null search would match everything and is treated as a misuse (callers should use the non-search row path instead).

Source

Thrown at Editor/Mono/GUI/TreeView/TreeViewControl/TreeViewControlDataSource.cs:74

                {
                    m_RootItem = m_Owner.BuildRoot();
                    ValidateRootItem();
                }

                // Rows
                m_Rows = m_Owner.BuildRows(m_RootItem);
                if (m_Rows == null)
                    throw new NullReferenceException("RefreshRows should set valid list of rows.");

                // Custom row rects
                if (m_Owner.m_OverriddenMethods.hasGetCustomRowHeight)
                    m_Owner.m_GUI.RefreshRowRects(m_Rows);
            }

            public void SearchFullTree(string search, List<TreeViewItem<TIdentifier>> result)
            {
                if (string.IsNullOrEmpty(search))
                    throw new ArgumentException("Invalid search: cannot be null or empty", "search");

                if (result == null)
                    throw new ArgumentException("Invalid list: cannot be null", "result");

                var stack = new Stack<TreeViewItem<TIdentifier>>();
                stack.Push(m_RootItem);
                while (stack.Count > 0)
                {
                    TreeViewItem<TIdentifier> current = stack.Pop();
                    if (current.children != null)
                    {
                        foreach (var child in current.children)
                        {
                            if (child != null)
                            {
                                if (m_Owner.DoesItemMatchSearch(child, search))
                                    result.Add(child);

View on GitHub (pinned to 225b0fbdb5)

Solutions

1. Check string.IsNullOrEmpty(search) before calling SearchFullTree and use the normal row-building path instead.
2. Only call SearchFullTree when the user has entered non-whitespace search text.
3. Guard: if (string.IsNullOrWhiteSpace(search)) return;

Example fix

// before
dataSource.SearchFullTree(searchField, rows); // searchField could be empty

// after
if (!string.IsNullOrEmpty(searchField))
    dataSource.SearchFullTree(searchField, rows);
else
    AddExpandedRows(rootItem, rows);

if (!string.IsNullOrEmpty(search))
    dataSource.SearchFullTree(search, result);
else
    AddExpandedRows(root, result);

static bool HasSearchText(string s) => !string.IsNullOrEmpty(s);

When it happens

Trigger: Calling SearchFullTree(string.Empty, result); calling with a null search string; a search field that was cleared but SearchFullTree was still invoked.

Common situations: UI search box cleared by the user but the search method was called before checking the empty case; programmatic search with an uninitialized string.

Related errors

• visibleColumns should should not be set to an empty array. A
• Invalid list: cannot be null
• Invalid list: cannot be null
• Invalid argument: {dropPosition}
• The setting label can't be null or empty.

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/be297d79c2418df4. Report an issue: GitHub.