Above error happens when trying to mount some disk drive from another server via sshfs.
Example from fstab:
root@192.168.99.143:/mnt/touro /mnt/touro fuse.sshfs user,x-systemd.automount,defaults,_netdev,allow_other,identityfile=/root/.ssh/id_ed25519 0 0
Running mount -a produces above error.
Make sure you accepted the host key or re-accept it if it changes, by ssh-ing first into the target server e.g.
ssh -i /root/.ssh/id_ed25519 root@192.168.99.143