JSch: UnknownHostKey exception even when the hostkey fingerprint is present in the known_hosts file

Question

There are two questions about this exception already:

• JSchException: UnknownHostKey and
• com.jcraft.jsch.JSchException: UnknownHostKey

I

Answer 1

The problem is that you have added ECDSA host key to the known_hosts, as the ssh prefers that key type:

ECDSA key fingerprint is 11:5d:55:29:8a:77:d8:08:b4:00:9b:a3:61:93:fe:e5.

But JSch prefers RSA key, which it won't find in the known_hosts:

RSA key fingerprint is 50:db:75:ba:11:2f:43:c9:ab:14:40:6d:7f:a1:ee:e3

---

You probably need JCE to enable ECDSA In JSch.

See JSch Algorithm negotiation fail.

---

Or make ssh use RSA key with -o HostKeyAlgorithms=ssh-rsa.

See How can I force SSH to give an RSA key instead of ECDSA?