unoplatform/uno · error · InvalidOperationException

Name property is not set

Error message

Name property is not set

What it means

InvalidOperationException thrown by Reference.ProvideValue (System.Xaml, ported from Mono) when the Name property is null. x:Reference resolves an element by name via IXamlNameResolver; without a name there is nothing to resolve. Name is normally supplied via the Reference(string name) constructor or the constructor argument in markup.

Solutions

1. Supply Name via the Reference(string name) constructor or set the property before ProvideValue.
2. In XAML, ensure x:Reference has a name, e.g. {x:Reference MyElement}.
3. Guard at the call site: if (ref.Name is null) ref.Name = expectedName; before evaluation.

Example fix

// before
var r = new Reference();
r.ProvideValue(sp); // Name is null

// after
var r = new Reference("MyElement");
r.ProvideValue(sp);

static Reference RequireName(Reference r) => r.Name is null ? throw new InvalidOperationException("Reference.Name is required.") : r;

static bool IsReady(Reference r) => !string.IsNullOrEmpty(r.Name);

try { return r.ProvideValue(sp); } catch (InvalidOperationException ex) when (ex.Message.Contains("Name property is not set")) { r.Name = fallbackName; return r.ProvideValue(sp); }

When it happens

Trigger: Default-constructing Reference and calling ProvideValue without setting Name, or malformed x:Reference markup omitting the name.

Common situations: Programmatic construction that forgets the name, XAML where the x:Reference name attribute is missing/blank, or a binding producing null for the name.

Related errors

• Item in the array must be an instance of
• Name property is not set
• serviceProvider
• serviceProvider does not implement IXamlNameResolver
• Type property must be set before calling ProvideValue method

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/131ad1f1962b9e5b. Report an issue: GitHub.

Appendix: source

Thrown at src/SourceGenerators/System.Xaml/System.Windows.Markup/Reference.cs:57

		public Reference (string name)
		{
			Name = name;
		}

		[ConstructorArgument ("name")]
		public string Name { get; set; }

		public override object ProvideValue (IServiceProvider serviceProvider)
		{
			if (serviceProvider == null)
			{
				throw new ArgumentNullException ("serviceProvider");
			}

			if (Name == null)
			{
				throw new InvalidOperationException ("Name property is not set");
			}

			var r = serviceProvider.GetService (typeof (IXamlNameResolver)) as IXamlNameResolver;
			if (r == null)
			{
				throw new InvalidOperationException ("serviceProvider does not implement IXamlNameResolver");
			}

			var ret = r.Resolve (Name);
			if (ret == null)
			{
				ret = r.GetFixupToken (new string [] {Name}, true);
			}

			return ret;
		}
	}
}

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