Unable to restore Plesk backup: Global server security settings prohibits restore from unsigned or modified backups

Symptoms

• It is not possible to restore a Plesk backup that exists on a remote FTP server by going to Plesk > Tools & Settings > Backup Manager, while the following error is displayed:
  

  PLESK_ERROR: Error: Global server security settings prohibits restore from unsigned or modified backups. You can not restore from it, except your service provider explicitly allow it

• The backup file that is being restored was created on another Plesk server

Cause

Plesk backups have unique signatures and are generally made to be restored on the same Plesk server.

If you want to restore a Plesk backup that was created on another Plesk server, you need to use the corresponding option for this purpose, as explained in the following page of the Plesk Obsidian documentation:

Uploading Backup Files to Server | Plesk Obsidian documentation

Resolution

1. Log into Plesk as the main Administrator
2. Go to Tools & Settings > Backup Manager
3. Press on the date and time of the backup that you want to restore.
4. Near the bottom of the page, check the box Restore this backup despite the fact that it does not have a valid signature
5. Press Restore

Note: For Resellers and Customers, this option can be enabled in panel.ini by using the steps in this article