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:

  # plesk -v
  plesk: command not found

  or 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. Check if Plesk database exists using the command:

   # MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql -uadmin psa

   • if it exists and you are connected to psa database:

     MariaDB [psa]>

     then move to step 3.

   • if you get the error message:

     ERROR 1049 (42000): Unknown database 'psa'

     restore the Plesk database from the latest daily dump:

     # zcat /var/lib/psa/dumps/mysql.daily.dump.0.gz | sed -n '/-- Current Database: `psa`/,/-- Current Database:*/p' | MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql -uadmin

3. Download Plesk Installer:

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

4. Make the file executable:

   # chmod +x plesk-installer

5. Start Plesk Installer and install the missing packages:

   # ./plesk-installer

6. Proceed with the installation.

7. 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