Directly following the restart of Guardian, Conlog exited with the following error:

Dec  9 10:34:34 h1conlog2 conlog: ../ecm_cac.cpp: 515: event_handler: pv name: H1:GRD-SUS_OMC_USERMSG: args.status is not ECA_NORMAL: ca_message: No reasonable data conversion between client and server types: Exiting.
Dec  9 10:34:34 h1conlog2 conlog: ../conlog.cpp: 331: process_cas: Exception: boost: mutex lock failed in pthread_mutex_lock: Invalid argument Exiting.

This is the same thing that was seen last Tuesday, but with a different channel name (H1:GRD-SUS_OMC_USERMSG instead of H1:GRD-HPI_ETMY_USERMSG).

It has been restarted.