Article ID: 121024, created on Apr 10, 2014, last review on May 11, 2014

  • Applies to:
  • Plesk Automation 11.5

Symptoms

I am trying to generate migration list but the following error occurs during migration:

    # ppa-transfer generate-migration-list config.ini

    [ERROR] fetch-source| ABORT (by exception): fetch info from source servers
    [ERROR] | ABORT (by exception): fetch info from source servers
    [ERROR] | Exception:
    Traceback (most recent call last):
     File "/usr/lib/python2.7/site-packages/parallels/common/migrator_cli.py", line 34, in run
        options.method(migrator, options)
    .....
      File "/usr/lib/python2.7/site-packages/paramiko/channel.py", line 1084, in _wait_for_event
        raise e
    SSHException: Channel closed.
    [ERROR] | Unexpected error: 'Channel closed.', migration is aborted. See the traceback above for more information.

On the source server the following error is shown in /var/log/auth.log:

    Apr 11 00:13:42 web01 sshd[22210]: subsystem request for sftp
    Apr 11 00:13:42 web01 sshd[22210]: error: subsystem: cannot stat /usr/libexec/sftp-server: No such file or directory
    Apr 11 00:13:42 web01 sshd[22210]: subsystem request for sftp failed, subsystem not found

Cause

The issue is caused by SSH service configuration on the source server.

Resolution

The problem is in the /etc/ssh/sshd_config file:

# override default of no subsystems
Subsystem      sftp    /usr/libexec/sftp-server

The mentioned sftp-server is not available, it should point to the sftp-server in /usr/lib/openssh/sftp-server. Change /etc/ssh/sshd_config file as below:

# override default of no subsystems
#Subsystem      sftp    /usr/libexec/sftp-server
Subsystem      sftp    /usr/lib/openssh/sftp-server

After this change, reload the ssh service:

# /etc/init.d/ssh reload

Search Words

Channel closed

SSHException

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