I started getting the above error when launching Casper Admin & Remote on my main mac.
This error would appear when launching Casper Admin & Remote, before i could enter any credentials. Which got me thinking: keychain!!
Yep sure enough, I had a saved password in my keychain.. once i deleted that all was well.
Thanks that’s a good tip. I had this on a machine once before but luckily I was rebuilding it 😉