https://learn.microsoft.com/ja-jp/dotnet/api/system.windows.data.multibinding.notifyonvalidationerror?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
MultiBinding.NotifyOnValidationError Property (System.Windows.Data) | Microsoft Learn
Gets or sets a value that indicates whether to raise the Error attached event on the bound element.
property systemmultibindingwindowsdatamicrosoft