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

Symptoms

• Plesk is not accessible in a web browser 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 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:

  • on CentOS/RHEL-based distributions:

    # rpm -qa | grep plesk-core

  • on Debian/Ubuntu-based distributions:
    

    # apt list --installed | grep plesk-core

Cause

Plesk installation is corrupted because the Plesk packages have been removed. System 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.

   MYSQL_LIN: 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.