Unable to start migration on Plesk server: Command execution failed on the local server with non-zero exit code.

Symptoms

• Migration can not be started on a Plesk server with one of the errors below:

  PLESK_ERROR: Command execution failed on the local server with non-zero exit code.

  ---

  PLESK_ERROR: Failed to fetch basic information about resellers, clients and domains data from source servers
  Cause: Command execution failed on the local server with non-zero exit code.
  command: rsync -r --chmod=Fu=r,Du=rwx,go= --timeout=30 -e 'ssh -i /usr/local/psa/var/modules/panel-migrator/sessions/20230101000000/ssh-keys/id_rsa.203.0.113.2 -p 22 -o PasswordAuthentication=no -o StrictHostKeyChecking=no -o GSSAPIAuthentication=no' /usr/local/psa/admin/plib/modules/panel-migrator/backend/lib/python/parallels/plesk/source/legacy/extras/plesk_17_0_pmm_shared/ root@203.0.113.2:/root/plesk_migrator/plesk_migrator-3vg2rgqorhcffzc3exzx7ockhvn3i55v/pmm_agent
  exit code: 255
  stdout:
  stderr: root@203.0.113.2: Permission denied (publickey,password).
  rsync: connection unexpectedly closed (0 bytes received so far) [sender]
  rsync error: unexplained error (code 255) at io.c(228) [sender=3.2.3]
  That is a critical error, migration was stopped.

Cause

Disabled ssh-rsa signature method on the target server.
Manual connection attempt from the target server to the source with enabled debug returns the following output:

# ssh -vvv -i .ssh/id_rsa_migration root@203.0.113.2
debug1: send_pubkey_test: no mutual signature algorithm
debug2: we did not send a packet, disable method

Resolution

1. Connect to the target server via SSH.

2. Enable the algorithm by executing the command below:

   # printf "\nPubkeyAcceptedKeyTypes +ssh-rsa\n" >> /etc/ssh/ssh_config