Hi, I sent the following letter to asio mail list some time ago: ======================================= I have found the following problem with overlapped_ptr. There is complete method in win_iocp_overlapped_ptr: void complete(const boost::system::error_code& ec, std::size_t bytes_transferred) { if (ptr_) { ptr_->io_service_.post_completion(ptr_, 0, 0); ptr_ = 0; } } As you can see, post_completion does not uses arguments of complete. So it notifies handler with invalid values. ======================================= But I did not receive response from Chris. Where should I submit a ticket? Best Regards, Sergei