Описание тега ierrorhandler
In .NET, allows an implementer to control the fault message returned to the caller from a WCF service and optionally perform custom error processing such as logging.
According to MSDN:
Allows an implementer to control the fault message returned to the caller and optionally perform custom error processing such as logging.
It can provide a centralized location for responding to exceptions generated in a WCF service. Typically used to implement detailed logging of errors and/or customization of the information that is returned to the caller via a FaultException.