None of the sshd servers start

[slords]

All sshd servers fail to start with the following errors:

• /usr/sbin/sshd
  Could not load host key: /etc/ssh/ssh_host_rsa_key
  Could not load host key: /etc/ssh/ssh_host_ecdsa_key
  Could not load host key: /etc/ssh/ssh_host_ed25519_key
  sshd: no hostkeys available -- exiting.