ssh into an app fails: ssh: unable to authenticate, attempted methods [none publickey]

Thanks @tom93 for your reply.

Re logs:

$ fly ssh console
Connecting to fdaa:0:d9ee:a7b:96:81c2:fd83:2... complete
Error error connecting to SSH server: ssh: handshake failed: ssh: unable to authenticate, attempted methods [none publickey], no supported methods remain
$ fly logs
2023-01-27T13:34:28Z app[81c2fd83] dfw [info]2023/01/27 13:34:28 unexpected error: [ssh: no auth passed yet, user: 'root' does not exist]

I’ve tried it in FRA and DFW.

For context this is the simple Go app: GitHub - luebken/helloweb