Validation.HasError Attached Property
Gets a value that indicates whether any binding on the target element has a validation error.
Assembly: System.Windows (in System.Windows.dll)
XMLNS for XAML: Not mapped to an xmlns.
In Windows Phone, handlers for events, such as SizeChanged, can check any pending error state. Such event handlers might check for the Validation.HasError attached property on objects in code, but would either call the GetHasError method or call the GetValue method with the HasErrorProperty identifier.