Unable to start migration when a non-root system user is used in Plesk Migrator

Symptoms

When using a non-root system user in Plesk Migrator, the migration pre-check fails with one of the following error messages:

PLESK_ERROR: Failed to fetch basic information about resellers, clients and domains data from source servers
...
stderr: /bin/mkdir: cannot create directory ‘/root’: Permission denied

PLESK_ERROR: Failed to fetch basic information about resellers, clients and domains data from source servers
...
stderr: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
rsync: connection unexpectedly closed (0 bytes received so far) [sender]

PLESK_ERROR: SSH connection to the source server 'source' (203.0.113.2) can not be used: command "bin/true" executed by SSH returned non-zero exit code. Check that the user used to connect to the server has "/bin/sh" or "/bin/bash" as its shell.

Cause

The Plesk migration was started with a non-root user.

Resolution

Plesk Migrator requires a built-in root user for connection to the source server (using root password or SSH key).

Note: To migrate with a non-root user, refer to the instructions for migration from a server with custom hosting.