MaterialDesignInXAML/MaterialDesignInXamlToolkit · error · ArgumentNullException

passwordBox

Error message

passwordBox

What it means

ArgumentNullException(nameof(passwordBox)) in PasswordBoxHintProxy's constructor (HintProxyFabric.PasswordBox.cs:26). The proxy adapts a PasswordBox for the floating SmartHint; wrapping null is illegal. Thrown when the proxy is constructed with a null PasswordBox (internal/fork/test code).

Source

Thrown at src/MaterialDesignThemes.Wpf/HintProxyFabric.PasswordBox.cs:26

        public bool IsEmpty() => string.IsNullOrEmpty(_passwordBox.Password);

        public object Content => _passwordBox.Password;

        public bool IsLoaded => _passwordBox.IsLoaded;

        public bool IsVisible => _passwordBox.IsVisible;

        public bool IsFocused() => _passwordBox.IsKeyboardFocusWithin;

        public event EventHandler? ContentChanged;
        public event EventHandler? IsVisibleChanged;
        public event EventHandler? Loaded;
        public event EventHandler? FocusedChanged;

        public PasswordBoxHintProxy(PasswordBox passwordBox)
        {
            if (passwordBox is null) throw new ArgumentNullException(nameof(passwordBox));

            _passwordBox = passwordBox;
            _passwordBox.PasswordChanged += PasswordBoxPasswordChanged;
            _passwordBox.Loaded += PasswordBoxLoaded;
            _passwordBox.IsVisibleChanged += PasswordBoxIsVisibleChanged;
            _passwordBox.IsKeyboardFocusWithinChanged += PasswordBoxIsKeyboardFocusedChanged;
        }

        private void PasswordBoxIsKeyboardFocusedChanged(object sender, DependencyPropertyChangedEventArgs e)
            => FocusedChanged?.Invoke(this, EventArgs.Empty);

        private void PasswordBoxIsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
            => IsVisibleChanged?.Invoke(this, EventArgs.Empty);

        private void PasswordBoxLoaded(object sender, RoutedEventArgs e)
            => Loaded?.Invoke(this, EventArgs.Empty);

        private void PasswordBoxPasswordChanged(object sender, RoutedEventArgs e)

View on GitHub (pinned to 98edec3a0b)

Solutions

1. Pass a valid PasswordBox instance; resolve it from the actual control receiving the hint.
2. Do not construct PasswordBoxHintProxy directly; rely on HintProxyFabric to select the adapter.
3. In tests, use a real PasswordBox; confirm Style/Template does not produce a null target.

if (passwordBox is null)
    throw new ArgumentNullException(nameof(passwordBox));

// Let HintProxyFabric choose the adapter; do not construct PasswordBoxHintProxy directly.

static bool CanWrapPasswordBox(PasswordBox? passwordBox) => passwordBox is not null;

When it happens

Trigger: Constructing PasswordBoxHintProxy with a null PasswordBox; usually reached via the internal HintProxyFabric attached behavior. The public API does not construct the proxy directly.

Common situations: Test doubles/fakes; a broken Style/ControlTemplate that resolves the PasswordBox to null; reflection; library fork.

Related errors

• comboBox
• session
• session
• session
• owner

AI-assisted analysis of MaterialDesignInXAML/MaterialDesignInXamlToolkit@98edec3a0b (2026-08-13). Data as JSON: /api/errors/7240d9a401c524d2. Report an issue: GitHub.