Unable to access Plesk Onyx 17.5.3 or Plesk Onyx 17.8.11: The file /opt/psa/admin/htdocs/application.php is part of Plesk distribution. It cannot be run outside of Plesk environment.

Symptoms

When opening Plesk Onyx 17.5.3 or Plesk Onyx 17.8.11, the following error message is shown in a web-browser:

The file /opt/psa/admin/htdocs/application.php is part of Plesk distribution. It cannot be run outside of Plesk environment.

Cause

The issue is with Domain Traffic Monitor extension on Plesk Onyx 17.5.3 / Plesk Onyx 17.8.11 with old update.

Resolution

1. Connect to the Plesk server via SSH.

2. Temporarily disable the Domain Traffic Monitor extension:

   # plesk bin extension --disable traffic-monitor

3. Apply one of the following steps:

   • for Plesk Onyx 17.5.3:

     Upgrade to Plesk Obsidian

   • for Plesk Onyx 17.8.11:

     Upgrade to Plesk Obsidian or update Plesk Onyx 17.8.11 to the latest micro-update with the command:

     # plesk installer update

4. Enable the extension back.