Plesk shows the error: Trait 'PleskExt\<ext_name>\path\to\file.php' not found (CustomButtons.php:11)

Symptoms

• Plesk interface shows one of the following error messages:

  PLESK_INFO: ERROR: Trait 'PleskExt\Catalog\Helper\PermissionsTrait' not found (CustomButtons.php:8)

  ---

  PLESK_INFO: ERROR: Trait 'PleskExt\Advisor\Helper\ProductInfo' not found (CustomButtons.php:12)

  ---

  PLESK_INFO: ERROR: Trait 'PleskExt\SslIt\CertificateIssuance\CertSubjectGeneratorAwareTrait' not found (Permissions.php:11)

  ---

  PLESK_INFO: ERROR: Trait 'PleskExt\SslIt\PleskExtensions\PleskExtensions' not found (Permissions.php:11)

• The Extensions menu is not opening with one of these error messages:

  PLESK_INFO: Cannot send headers; headers already sent in /opt/psa/admin/plib/modules/sslit/library/Config.php, line 1

  ---

  PLESK_INFO: Cannot send headers; headers already sent in /usr/local/psa/admin/plib/modules/sslit/library/Config.php, line 1
  

  ---

  PLESK_INFO: Error Message:Class `PleskExt\Catalog\Cache\Persistent` not found

• In Plesk Obsidian, when clicking Repair All or Check All at Tools & Settings > Diagnose & Repair, the following error appears:

  PLESK_INFO: this.getDate(...).map is not a function

Cause

Installation of the extension (highlighted in the error) is corrupted.

Resolution

Reinstall the extension:

1. Connect to the Plesk server via SSH (Linux) / RDP (Windows Server).

2. Run the command below to reinstall the extension (on Windows Server, use a command prompt as an Administrator):

   # plesk bin extension --install <extension_name>

   where <extension name> is the name of the extension mentioned after PleskExt\ in the error message. Use lowercase letters only in the command.

   Example:

   If the error is:

   PLESK_INFO: Trait 'PleskExt\Catalog\Helper\PermissionsTrait' not found (CustomButtons.php:8)

   then use the command:

   # plesk bin extension --install catalog

   Note: If the error still appears on the Home page in Plesk, apply the resolution steps from this KB article.