dotnet/maui · error · XamlParseException

Can't resolve {parts[0]}

Error message

Can't resolve {parts[0]}

What it means

XamlParseException raised after the converter walked the parent chain for a single-segment property name but could not determine an owning Type. It tried Setter/Style, TriggerBase, VisualState, Trigger, and PropertyCondition branches; none matched, so type stayed null and the converter refuses to guess which BindableProperty the bare name refers to.

Source

Thrown at src/Controls/src/Core/BindablePropertyConverter.cs:60

					throw new XamlParseException(msg, lineinfo);
				}
				object parent = parentValuesProvider.ParentObjects.Skip(1).FirstOrDefault();
				if (parentValuesProvider.TargetObject is Setter)
				{
					if (parent is Style style)
						type = style.TargetType;
					else if (parent is TriggerBase triggerBase)
						type = triggerBase.TargetType;
					else if (parent is VisualState visualState)
						type = FindTypeForVisualState(parentValuesProvider, lineinfo);
				}
				else if (parentValuesProvider.TargetObject is Trigger)
					type = (parentValuesProvider.TargetObject as Trigger).TargetType;
				else if (parentValuesProvider.TargetObject is PropertyCondition && parent is TriggerBase)
					type = (parent as TriggerBase).TargetType;

				if (type == null)
					throw new XamlParseException($"Can't resolve {parts[0]}", lineinfo);

				return ConvertFrom(type, parts[0], lineinfo);
			}
			if (parts.Length == 2)
			{
				if (!typeResolver.TryResolve(parts[0], out type))
				{
					string msg = string.Format("Can't resolve {0}", parts[0]);
					throw new XamlParseException(msg, lineinfo);
				}
				return ConvertFrom(type, parts[1], lineinfo);
			}
			throw new XamlParseException($"Can't resolve {value}. Syntax is [[prefix:]Type.]PropertyName.", lineinfo);
		}

		public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
		{
			var strValue = value?.ToString();

View on GitHub (pinned to f377ff1c5e)

Solutions

1. Qualify the property with its owner type: Property="VisualElement.BackgroundColor".
2. Move the Setter into a recognized parent (Style, Trigger, or VisualStateGroup/VisualState chain).
3. If the parent is a custom TriggerBase, ensure it exposes TargetType so the converter can read it.

Example fix

<!-- before -->
<Setter Property="BackgroundColor" Value="Red" />

<!-- after -->
<Setter Property="VisualElement.BackgroundColor" Value="Red" />

// Prefer qualified property names in Setters that may sit in non-standard parents:
// Property="VisualElement.BackgroundColor"

try { /* compile XAML */ }
catch (XamlParseException ex) when (ex.Message.Contains("Can't resolve"))
{
    // instruct the author to qualify the property name
}

When it happens

Trigger: A bare property name inside an element whose parent chain is not one of the recognized shapes (Setter in Style/Trigger/VisualState). For example a Setter nested in an unsupported container, or a custom markup that places Setter somewhere the converter does not look.

Common situations: Hand-authored or tool-generated XAML that nests Setter/Trigger in unusual parents; custom TriggerBase subclasses; XAML written for an older API surface that has since changed parent expectations.

Related errors

• Can't resolve {name} on {type.Name}
• Can't resolve {0}
• Can't resolve {value}. Syntax is [[prefix:]Type.]PropertyNam
• The PropertyName of {type.Name}.{name} is not {propertyName}
• XC0040

AI-assisted analysis of dotnet/maui@f377ff1c5e (2026-08-13). Data as JSON: /api/errors/06b378b0a5798c67. Report an issue: GitHub.