The error message "Node.js application in the subscription already uses this application root" in Plesk indicates that there's already a Node.js application configured with the same application root directory in the subscription.

Here's what you can do to resolve this issue:

1. Review Existing Node.js Applications:

   • In Plesk, go to the subscription where the Node.js application is configured. Check if there's already a Node.js application using the same application root directory.

2. Change Application Root Directory:

   • If you have multiple Node.js applications in the same subscription and you want to use the same application root, you'll need to adjust the application root directory of one of the applications to a different location.

3. Create a New Application Root:

   • If you need to create a new Node.js application with a different application root, choose a directory that hasn't been used by any other Node.js application in the same subscription.

4. Check for Symlinks or Conflicts:

   • Verify that there are no symbolic links or conflicting configurations that might be causing the issue. Sometimes, symbolic links or duplicate configurations can lead to conflicts.

5. Clear Application Cache:

   • If you've made any recent changes, clear the cache of your Node.js application to ensure that any previous configurations are properly updated.

6. Restart Node.js Application:

   • After making any changes, restart your Node.js application to apply the new settings.

7. Check Logs for Details:

   • Review the logs of your Node.js application for any error messages or warnings that might provide more context about the issue.

8. Contact Plesk Support:

   • If you're unable to resolve the issue using the above steps, consider reaching out to Plesk support for further assistance. They can provide specific guidance based on your server's configuration.

It's important to ensure that each Node.js application in a subscription has a unique application root directory to prevent conflicts. Additionally, always make backups of your applications and configurations before making significant changes.