Unable to update Plesk: An error occurred during performing of installation PREP actions. Installation was rolled back

Symptoms

• The following message can be found on running Plesk Update via CLI:

  CONFIG_TEXT: Another instance of bootstrapper is already running. Please wait until it finishes.
  If you are completely sure there is no other instance running,
  just remove /var/lock/parallels-panel-bootstrapper-running.lock file and retry.
  Note: running more than one instance at once may badly damage your system.

• Update finishes with the following error;

  CONFIG_TEXT: ERROR: An error occurred during performing of installation PREP actions (see log for details). Installation was rolled back.
  Warning! Not all packages were installed.
  Please check if your system services are operable.
  Please resolve this issue and try to install the packages again.
  Visit https://support.plesk.com/ to search for a solution.
  exit status 1

• There is a stuck bootstrapper process:

  # ps auxww | grep bootstrapper
  root 5381 0.0 0.0 13800 776 ? S 2021 0:00 /bin/bash -hB /usr/local/psa/bootstrapper/pp18.0.36-bootstrapper/bootstrapper.sh perform-deferred-actions

Cause

The stuck bootstrapper process prevents Plesk Installer from processing packages.

Resolution

1. Connect to the server via SSH.

2. Find the bootstrapper process ID number (PID) from the output of:

   # ps auxww | grep bootstrapper

   See below example where the second column is the PID:

   CONFIG_TEXT: root 5381 0.0 0.0 13800 776 ? S 2021 0:00 /bin/bash -hB /usr/local/psa/bootstrapper/pp18.0.36-bootstrapper/bootstrapper.sh perform-deferred-actions

3. Kill bootstrapper processes with the PID number, on this example '5381':

   # kill -9 5381

   Note: Replace '5381' it with the actual result from previous step.

4. Remove the bootstrapper lock file:

   # rm /var/lock/parallels-panel-bootstrapper-running.lock

5. Re-run Plesk installer process.