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

Symptoms

• Plesk Obsidian running on a Linux-based operating system

• The following message appears while attempting a Plesk update via CLI:

  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.

• The update finishes with the following error:

  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

• Further review of the currently running processes reveals 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 the Plesk Installer from processing packages and thus causes the error.

Resolution

1. Connect to the server via SSH

2. Find the bootstrapper process ID number (PID) by viewing the output of the following command:

   # ps auxww | grep bootstrapper

   See below example where the second column is the PID:

   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 by running the following command (in this example, the process ID is 5381):

   # kill -9 5381

   Note: Replace 5381 it with the exact ID of the bootstrapper process in your case previous step.

4. Remove the bootstrapper lock file by executing the following command:

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

5. Run the Plesk installer update process once again by using the information in this article:
   How to update Plesk Obsidian to the latest build?