unoplatform/uno · error · Exception

Unable to find the type {typeName} in key {resource.Key}

Error message

Unable to find the type {typeName} in key {resource.Key}

What it means

Thrown when parsing a resource key that uses the 'using:Namespace.Type.Property' pattern. The type portion is extracted and looked up via FindTypeByFullName; if the type cannot be found, the exception includes both the type name and the resource key.

Source

Thrown at src/SourceGenerators/Uno.UI.SourceGenerators/XamlGenerator/XamlFileGenerator.Reflection.cs:858

				const string usingPattern = "[using:";

				if (propertyPath.StartsWith(usingPattern, StringComparison.Ordinal))
				{
					var lastDotIndex = propertyPath.LastIndexOf('.');

					var propertyName = propertyPath.Substring(lastDotIndex + 1);
					var typeName = propertyPath
						.Substring(usingPattern.Length, lastDotIndex - usingPattern.Length)
						.Replace("]", ".");

					if (_metadataHelper.FindTypeByFullName(typeName) is INamedTypeSymbol typeSymbol)
					{
						yield return (typeSymbol, propertyName);
					}
					else
					{
						throw new Exception($"Unable to find the type {typeName} in key {resource.Key}");
					}
				}
			}
		}
	}
}

View on GitHub (pinned to 0418340488)

Solutions

1. Verify the fully-qualified type name in the 'using:' key matches a real type.
2. Ensure the assembly containing the type is referenced by the project.
3. Check for namespace changes after refactoring and update the key accordingly.

Example fix

<!-- before -->
<ResourceDictionary>
  <x:String x:Key="using:MyApp.OldNs.MyType.MyProp">Value</x:String>
</ResourceDictionary>
<!-- after -->
<ResourceDictionary>
  <x:String x:Key="using:MyApp.NewNs.MyType.MyProp">Value</x:String>
</ResourceDictionary>

// Verify the type in a 'using:Namespace.Type.Property' resource key resolves:
// var typeName = "MyApp.Models.MyType";
// var type = Type.GetType(typeName + ", MyApp.Models");
// if (type == null) Console.WriteLine($"Type {typeName} not found — check resource key");

When it happens

Trigger: A resource dictionary entry uses a key like 'using:MyApp.Models.MyType.MyProperty' where 'MyApp.Models.MyType' does not resolve to a known type in the compilation.

Common situations: The type namespace was renamed or the type was moved; the assembly containing the type is not referenced; typo in the namespace or type name in the resource key; the 'using:' pattern was applied to a non-static-property scenario incorrectly.

Related errors

• The type '{fullyQualifiedMetadataName}' is not found.
• Unable to resolve {symbol} (Reason: {errorTypeSymbol.Candida
• No valid setter found for attached property {name}
• Unable to find type {fullName}
• The type {0} could not be found

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/b5aaf825d176d5b9. Report an issue: GitHub.