I'm running a web app on a Linux server which connects to other servers. When I run the project on my Play framework on loclhost it runs fluently. When I run it on my Linux server I get the above message 3 times, one for each server. I read a post about it where it says that it is a man in the middle warning and if I write yes it should work. But though a write yes, nothing happens and the app doesn't run, and the error message keeps popping up. I tried creating private and public keys and add them to the authorized_keys file, but it didn't work either. What should I so to run my app?