Unable to start the migration: Permission denied (password) or id_rsa.203.0.113.2 not accessible

Symptoms

Migration fails with the following error:

stderr: Warning: Permanently added '' (ECDSA) to the list of known hosts.
Permission denied (password).
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: unexplained error (code 255) at io.c(605) [sender=3.0.9]

rsync: link_stat "/root/plesk_migrator/plesk_migrator-oz6929f30l2tcyvgpihulq5o5quo7ogo/backup.tar" failed: No such file or directory (2)
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1659) [Receiver=3.1.3]
rsync: [Receiver] write error: Broken pipe (32)

Warning: Identity file /usr/local/psa/var/modules/panel-migrator/sessions/20210302092601/ssh-keys/id_rsa.203.0.113.2 not accessible: No such file or directory.

Cause

SSH key authentication is disabled on the source server.

Resolution

1. Log into the source server via SSH.
2. Using the vi text editor open the /etc/ssh/sshd_config file.
3. Change the line below from:

   PubkeyAuthentication no

   To 

   PubkeyAuthentication yes

4. Save the changes.
5. Reload sshd service:

   # service sshd reload