Extensions catalog is missing or does not load in Plesk: Internal server error

Symptoms

• "Extensions" button is absent in the left sidebar in Plesk.

• When opening the Extensions URL directly at https://<server_ip_address_or_hostname>:8443/modules/catalog/index.php/catalog/featured, the page fails to load with:

  PLESK_WARN: Internal server error

Cause

Extensions catalog installation is corrupted/missing.

Resolution

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

2. Reinstall Extensions Catalog:

   Note: On Windows Server, start a command prompt as an Administrator.

   # plesk bin extension --install catalog