Unable connect to the Plesk server via SFTP: subsystem request for sftp failed, subsystem not found

Symptoms

• Unable connect to the Plesk server via SFTP, the error below is shown:

  subsystem request failed on channel 0
  Couldn't read packet: Connection reset by peer

• The following errors can be found in /var/log/syslog or /var/log/messages log file:

  www sshd[16588]: error: subsystem: cannot stat /usr/libexec/sftp: No such file or directory
  www sshd[16588]: subsystem request for sftp failed, subsystem not found

Cause

The incorrect path to SFTP is set in the sshd configuration.

Resolution

1. Log into the server via SSH.
2. Verify that the /usr/libexec/openssh/sftp-server file is presented on the server:

   # ls -l /usr/libexec/openssh/sftp-server
   -rwxr-xr-x 1 root root 100784 Aug 9 2019 /usr/libexec/openssh/sftp-server

3. Using the vi text editor open the /etc/ssh/sshd_config file and specify value for Subsystem directive as shown below:

   Subsystem sftp /usr/libexec/openssh/sftp-server

4. Restart the sshd service:

   # service sshd restart