dotnet/maui · error · ArgumentException

path cannot be an empty string

Error message

path cannot be an empty string

What it means

ArgumentException from the Binding constructor when path is non-null but empty or whitespace. The constructor first rejects null path with ArgumentNullException, then this check rejects blank paths because a binding needs a real property path. Path is the primary identifier of the source member to bind.

Source

Thrown at src/Controls/src/Core/Binding.cs:46

		public Binding()
		{
		}

		/// <summary>
		/// Initializes a new instance of the <see cref="Binding"/> class with the specified path, mode, converter, and source.
		/// </summary>
		/// <param name="path">The property path to bind to.</param>
		/// <param name="mode">The binding mode.</param>
		/// <param name="converter">The value converter to use.</param>
		/// <param name="converterParameter">The parameter to pass to the converter.</param>
		/// <param name="stringFormat">The string format to apply to the bound value.</param>
		/// <param name="source">The source object for the binding.</param>
		public Binding(string path, BindingMode mode = BindingMode.Default, IValueConverter converter = null, object converterParameter = null, string stringFormat = null, object source = null)
		{
			if (path == null)
				throw new ArgumentNullException(nameof(path));
			if (string.IsNullOrWhiteSpace(path))
				throw new ArgumentException("path cannot be an empty string", nameof(path));

			Path = path;
			Converter = converter;
			ConverterParameter = converterParameter;
			Mode = mode;
			StringFormat = stringFormat;
			Source = source;
		}

		/// <summary>
		/// Gets or sets the converter used to convert values between the source and target.
		/// </summary>
		public IValueConverter Converter
		{
			get { return _converter; }
			set
			{
				ThrowIfApplied();

View on GitHub (pinned to f377ff1c5e)

Solutions

1. Supply a non-empty property path, e.g. nameof(MyViewModel.Title).
2. If the path is computed, validate !string.IsNullOrWhiteSpace(path) before constructing the Binding.
3. Use the Self binding source (BindingMode) or a relative source if you intentionally need no path.

Example fix

// before
var b = new Binding(_pathField);

// after
if (string.IsNullOrWhiteSpace(_pathField))
    throw new InvalidOperationException("Binding path must be set.");
var b = new Binding(_pathField);

if (string.IsNullOrWhiteSpace(path))
    throw new ArgumentException("Binding path is required.", nameof(path));
var binding = new Binding(path);

static bool IsValidBindingPath(string path) =>
    !string.IsNullOrWhiteSpace(path);

When it happens

Trigger: new Binding("") or new Binding(" "); building a Binding with a path variable that came back empty (e.g. nameof() on a private field in a context where it returned ""); constructing bindings from data that yielded an empty string.

Common situations: Dynamic binding construction from user/mapped data; refactor where the bound member was removed and nameof returned an unexpected token; copy-paste leaving the path blank.

Related errors

• propertyName
• returnType
• declaringType
• Cannot apply relative binding when the target object is null
• indexPath

AI-assisted analysis of dotnet/maui@f377ff1c5e (2026-08-13). Data as JSON: /api/errors/dbb492470056113d. Report an issue: GitHub.