I see similar messages fairly often. I believe "Success" is what you get when you use strerror() to translate an errno of 0 (success) on a Linux/UNIX machine with English localization. So this contradictory message is what happens when the programmer uses an errno-printing function (perror() or something custom) to indicate an error that wasn't actually due to a failure that sets errno.
I had one of those once so I winced when I saw it. I was printing 'Error: ' with the message that came back from the server and in one case saw 'Error: Success'.
I'm pretty sure that was his SSH connection dying after he killed the remote server. But yeah, it's hilariously/depressingly contradictory. Worse than useless, since you don't know if something went right, or something went wrong, or both, or neither!
Yeah, could've been something like that. It doesn't normally do that it was just a one-off, so I figured it was just something weird up (like maybe I'd already told it to reboot and it didn't seem to work, so I sent it again but it was just starting).