rdiff-backup error: Host key verification failed-Collection of common programming errors

It looks like your connection is failing because the ssh host key of your target host has changed:

Host key verification failed.

Because of this error your ssh connection is failing. You need to either update the cached host key on your local system, or figure out why the host key on the remote system has changed. You can update your local key like this:

# ssh-keygen -R 161.3.46.12
# ssh [email protected]

This should prompt you to accept the new host key.

Do note that host key verification is a fatal error for a reason; it can mean that your remote server has been compromised. More often it means that someone has re-installed a system without preserving the host key.