Why does the send (winsock2) method return SOCKET_ERROR and the error code is 0?

Question

Delphi

res := Send(FSocketNative, FBufferPartOut.Data[0], FBufferPartOut.Header.Size, 0);

if res = -1 then begin
      WSAError := WSAGetLastError;
      res := GetLastError;
end;

After writing to the socket res = -1. And the error code = 0. Both WSAGetLastError and GetLastError return 0.
Who can tell why this occurs?

Answer 1

So go through the debugger until you get the error yourself