Unable to start migration using 'root' user and its password in Plesk Migrator: Failed to connect to the source domain by SSH: Bad authentication type

Symptoms

When starting migration using 'root' user and its password in Plesk Migrator, the initialization fails with one of the following error messages:

PLESK_ERROR: Failed to check SSH connection to the source server 'source' (203.0.113.2): Unable to connect to '203.0.113.2' by SSH: Bad authentication type; allowed types: ['publickey'].
Ensure that the server is up and there are no firewall rules that may block SSH connections to the server,
then restart migration.

PLESK_ERROR: Failed to perform action: Fetch data from source cPanel
Cause: Failed to connect to the the source server 'cpanel' (203.0.113.2) at '203.0.113.2' by SSH as 'root': ('Bad authentication type', [u'publickey', u'gssapi-keyex', u'gssapi-with-mic']) (allowed_types=[u'publickey', u'gssapi-keyex', u'gssapi-with-mic']) 
That is a critical error, migration was stopped.

Cause

Password authentication (and/or root authentication) is disabled on the source server.

Resolution

1. Connect to the source server via SSH.

2. Open /etc/ssh/sshd_config file in a text editor. In this example, we are using vi editor:

   # vi /etc/ssh/sshd_config

3. Set PasswordAuthentication and PermitRootLogin directives to 'yes' and remove '#' at the beginning of each line as shown below:

   CONFIG_TEXT: PermitRootLogin yes
   PasswordAuthentication yes

4. Save the changes and close the file.

5. Verify that these directives are defined in /etc/ssh/sshd_config only: not defined in other .conf files inside /etc/ssh:

   # grep -ir PasswordAuthentication /etc/ssh | grep -v '#'
   /etc/ssh/sshd_config:PasswordAuthentication yes

   # grep -ir PermitRootLogin /etc/ssh | grep -v '#'
   /etc/ssh/sshd_config:PermitRootLogin yes

   Note: If these directives are defined in other .conf files inside /etc/ssh, remove them form these files.

6. Restart SSH service:

   # service sshd restart

7. Restart migration.

Additional Information

To migrate with a non-root user, see:

• Migrating From a Linux Server With Custom Hosting - Plesk Migration Guide