Plesk and its command-line utilities do not work due to missing Plesk packages

Symptoms

• Plesk is not accessible with a "404 Not found nginx" error or a blank page.

• Plesk command-line utilities are unavailable, for example:

  # plesk bin domain -l
  Unknown Plesk command-line utility: "domain"

  # plesk login
  Unknown Plesk command-line utility: "admin"

• Plesk version cannot be retrieved:

  # plesk -v
  open /usr/local/psa/version: no such file or directory

• The plesk-core package is missing on the server:
  For RHEL-based OS:

  # rpm -qa | grep plesk-core

  For Debian-based OS:

  # apt list --installed | grep plesk-core

Cause

The Plesk installation is corrupted. Plesk Packages and Plesk directories are missing or corrupted. This situation can occur if a Plesk or system package update was interrupted by a system reboot or forced stopping of update-related processes. Package manager logs may indicate that Plesk packages have been removed recently:

• • On CentOS/RHEL-based distributions:

    # grep Erased /var/log/yum.log | grep 'psa|plesk'
    Nov 01 10:00:00 Erased: psa-firewall-17.8.11-cos7.build1708180301.19.x86_64
    Nov 01 10:00:00 Erased: psa-updates-17.8.11-cos7.build1708180326.12.noarch
    Nov 01 10:00:00 Erased: plesk-core-17.8.11-cos7.build1708180301.19.x86_64
    <...>

  • On Debian/Ubuntu-based distributions:

    # grep remove /var/log/dpkg.log | grep 'psa|plesk'
    2018-01-01 10:00:00 remove psa-mnemo:all 4.2.14-debian8.0.build1708180425.15 <none>
    2018-01-01 10:00:00 remove psa-updates:all 17.8.11-debian8.0.build1708180326.12 <none>
    2018-01-01 10:00:00 remove plesk-core:amd64 17.8.11-debian8.0.build1708180301.19 <none>
    <...>

Resolution

1. Connect to the Plesk server via SSH.

2. Download Plesk Installer:

   # wget http://autoinstall.plesk.com/plesk-installer

3. Make the file executable:

   # chmod +x plesk-installer

4. Start Plesk Installer and install the missing packages:

   # ./plesk-installer

5. On the Main components list for Plesk page, select Plesk for installation and proceed further.

   Main components list for Plesk
   ========================================

   31 of 55 components selected

   Please select the components of Plesk you want to install:

   1. [*] Plesk
   2. [=] BIND DNS server
   ...

   Note: If Plesk Installer fails with the error " Unknown database 'psa'", restore the psa database according to this KB article first.

6. On Debian/Ubuntu-based distributions, re-link Plesk installation directory using these commands:

   # unlink /usr/local/psa
   # rm -rf /usr/local/psa
   # ln -s /opt/psa /usr/local/psa

7. Log in to Plesk.