Hi, One of the debug statement is removed in mux.c and there is no history for the same. The line number after 1989. switch (type) { case MUX_S_SESSION_OPENED: if ((r = sshbuf_get_u32(m, &sid)) != 0) fatal("%s: decode ID: %s", __func__, ssh_err(r)); debug("%s: master session id: %u", __func__, sid); <------------ This particular line is removed in oepnssh 8.1p1 break; This is a very useful statement to check when CONTROLPERSIST feature is used. This gives out the "master session id: sid" when ssh is run in debug mode. Could you please check whether this was deliberately removed or this was accidentally removed. Thanks and Regards, Pradeep