Hi, I am getting confused, could anyone clarify the following points? (Note that I am in a single thread context) 1- After a call to socket.async_send_to(buffer, remote_endpoint, write_handler) followed by a call to socket.cancel() is it possible that the write operation completed before I called cancel() and that my write_handler will be called with no error? 2- After a call to socket.async_send_to(buffer, remote_endpoint, write_handler) followed by a call to socket.cancel() is it possible that some data has actually been written to the socket (let's assume the buffer is quite big) and that then, the operation has been canceled? In such case, would my write_handler be called with both boost::asio::placeholders::error set AND boost::asio::placeholders::bytes_transferred equal to the partial data that has been written? Thanks, Laurent