I got this error when I was trying to create a watcher by using email action. Weird thing is that each time I tried to create the email action watcher, it not only gave me the error, but also kicked me out of the website and I had to log in again. I checked the log and seemed like the kibana was forced to restart itself for no reason. It was no problem with log watcher setup though.
Anyone has ideas what is wrong with my kibana setting? Thanks!