How to install the Plesk Extension Manager on a new server

The Plesk Extension Manager allows you to install, update, and manage third-party add-ons directly from the Plesk interface. These steps target Plesk Obsidian 18.x running on Ubuntu 24.04 or AlmaLinux 9. You will configure the repository and enable the feature to access the official marketplace.

Prerequisites

• Operating System: Ubuntu 24.04 LTS or AlmaLinux 9
• Plesk Version: Plesk Obsidian 18.x (Linux)
• Privileges: Root access or a user with sudo privileges
• Network: Internet connection to reach the Plesk Extension Manager repository
• Software: Plesk Panel installed and updated to the latest minor version

Step 1: Update the Plesk system

Before installing any new component, ensure your Plesk system is up to date. This prevents conflicts between the core panel and the new extension manager package. Run the update command to fetch the latest repository metadata and upgrade existing packages.

sudo apt update
sudo apt upgrade -y

Wait for the process to complete. You will see output indicating the number of packages upgraded. If you are on AlmaLinux, use dnf instead of apt.

sudo dnf update -y

Step 2: Install the Plesk Extension Manager repository

The Extension Manager is not always included in the default Plesk installation on fresh servers. You must add the specific repository key and source list to enable the package. On Ubuntu systems, the repository is typically located in the Plesk official sources.

sudo apt install plesk-extension-manager -y

On AlmaLinux or CentOS Stream, the package name might differ slightly depending on the specific Plesk channel. Use the following command if the package is not found in the default repo:

sudo dnf install plesk-extension-manager -y

If you encounter a dependency error, install the missing libraries first:

sudo apt install python3-pip -y
sudo pip3 install plesk-extension-manager

Step 3: Configure the Extension Manager settings

Once the package is installed, you must configure the manager to point to the correct Plesk API endpoint. Open the configuration file located in the Plesk directory structure. Edit the file to ensure the API URL matches your server's hostname.

sudo nano /etc/plesk/extmanager/config.ini

Add or modify the api_url parameter. Replace your-server-ip with your actual server hostname or IP address.

[main]
api_url = https://your-server-ip:8443/plesk/bin/api

Save the file and exit the editor. Restart the Plesk service to apply the new configuration.

sudo systemctl restart plesk

Step 4: Enable the Extension Manager service

Ensure the service responsible for handling extension requests is active. Check the status of the Plesk daemon to confirm it is running without errors.

sudo systemctl status plesk

If the service is not active, start it immediately. This step allows the Plesk interface to communicate with the external extension repository.

sudo systemctl start plesk

Verify the installation

To confirm the Extension Manager is installed correctly, log in to the Plesk Control Panel as root. Navigate to the Tools & Settings section. Click on Extensions. You should see a list of available third-party add-ons, including the Plesk Extension Manager itself. If the list loads without errors, the installation is successful.

You can also run the following command to verify the package is registered in the system:

dpkg -l | grep plesk-extension-manager

The output should show the package name and version installed, for example plesk-extension-manager 1.0.0.

Troubleshooting

If you encounter issues during the installation or configuration, refer to the following common errors and their fixes.

Error 1: Repository not found
If you receive an error stating that the repository cannot be found, your Plesk version might be outdated. Run sudo apt update and then reinstall the package using the command from Step 2. Ensure your system clock is synchronized using timedatectl set-ntp true.

Error 2: Permission denied
If you cannot edit the configuration file, you do not have the necessary permissions. Run the command with sudo or switch to the root user using su -.

Error 3: Service fails to start
Check the Plesk logs for specific error messages. Run sudo tail -f /var/log/plesk/plesk.log to watch for errors in real-time. If the service fails due to a missing library, install it using sudo apt install libssl3.

Error 4: API connection refused
If the Extension Manager cannot connect to the API, ensure port 8443 is open on the server firewall. Run sudo ufw allow 8443/tcp to allow traffic on the Plesk API port.