Hi all, I have defined an io_service that is used by two sockets, one of them uses tcp, and the other udp. When the callback of this async_read_some is called socket.async_read_some(boost::asio::buffer(readBuffer), boost::bind(&RequestHandler::onRead, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); A udp socket is created with the same io_service and an async_receive_from is called. On the callback of this read operation I try to write to the tcp socket but it captures an exception with message: "unknown exception". When this happens, the client that is listening to the tcp socket, receives "End of file" error. I resolved this problem with an io_service per socket but I would like to use the same io_service. Someone has any idea why this happens? Thanks! Victoria