Another solution, without a reboot, similar to the above:
Run from shell as root "/usr/sbin/sshd": and review the errors:
"Could not load host key: /etc/ssh/ssh_host_rsa_key
Could not load host key: /etc/ssh/ssh_host_dsa_key
Could not load host key: /etc/ssh/ssh_host_ecdsa_key
Disabling protocol version 2. Could not load host key
Sshd: no hostkeys available -- exiting"
Solution that worked for me, perform keygen and overwrite for each error, so for the above:
as root from shell:
"ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key"
"ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key"
"ssh-keygen -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key"
Run from shell as root "/usr/sbin/sshd": should be no errors or complaints. ssh works now