EIdNotASocket = class(EIdSocketError);

EIdNotASocket is an EIdSocketError descendant that represents the exception raised when a socket operation is performed using an invalid socket handle. 

EIdNotASocket is created in RaiseSocketError when the error number for the last socket operation contains Id_WSAENOTSOCK. The message for the exception will contain the value in the resource string RSStackENOTSOCK. 

Please note that you can add EIdNotASocket to the list of ignored exceptions in the IDE. This will treat EIdNotASocket just like silent exceptions in the IDE. Your program will still run correctly, but the debugger will not stop on it.