Hi mytom,
It is not possible to tell just from this log what the issue may be. It could be that an error occurred when a zenon component attempted to send a log message to the diagnosis server. Such a component can be the zenon editor or a driver started by the editor when importing variables but it could also be zenon runtime or a driver in the runtime.
Do I understand correctly, that you were working with the zenon editor when this message appeared? What was the last action before this error occurred?
In general, we recommend configuring the diagnosis server for local logging only. Also we recommend having a separate system with the zenon editor and install only the runtime on operator panels.
Best regards,
Mark