Plesk upgrade or update fails: ERROR while trying to check the hostname

Symptoms

• Plesk installer shows a warning at the beginning of upgrade running from a web-based interface:

  Your host name must resolve to the correct IP address of your server, unless you are using network address translation (NAT).
  Please quit Parallels Installer, fix the host name resolution problem,
  and then try installing again.
  You can skip the hostname check and continue the installation, however,
  in such a case, the installer cannot guarantee a successful installation.

• Plesk upgrade to next release or Plesk updates installation fails:

  Can not bind a socket to address host.example.com:715 - Cannot assign requested address

  or

  Please specify the host name in the /etc/hosts file or specify DNS configuration in the /etc/resolv.conf on your system.
  ERROR while trying to check the hostname

  or

  Warning: Host name check failed.
  Can't bind to socket: Cannot assign requested address
  (hostname='example.com', ip=203.0.113.3)

Cause

Invalid hostname or IP address configuration in /etc/hosts or /etc/sysconfig/network.

Resolution

1. Connect to Plesk via SSH

2. Identify the server hostname and IP address:

   # hostname
   server.example.com

   # nslookup host.example.com
   …
   Name: server.example.com
   Address: 203.0.113.2

   If the server is behind NAT, use the private server IP address.

3. Set actual IP address and hostname in /etc/hosts file identified on previous step:

   203.0.113.2 server.example.com

   On CentOS7/CloudLinux7/RHEL7, the hostname can be specified as below:

   # hostnamectl set-hostname server.example.com