Plesk migration is stuck at the beginning: Preparing migration. Starting...

Symptoms

• Migration is stuck at the following stage:

  PLESK_INFO: Preparing migration
  Starting...

• In an attempt to access some Plesk folders, e.g. %plesk_dir%\admin\bin\, on the destination server under the Administrator account, the UAC (User Account Control) pop-up window appears:

  PLESK_INFO: You don't currently have permission to access this folder. Click Continue to permanently get access to this folder.

• In an attempt to reload source data via command line the next error occurs:

  C:\> "%plesk_dir%\admin\plib\modules\panel-migrator\backend\plesk-migrator.bat" generate-migration-list "%plesk_dir%/var/modules/panel-migrator/sessions/20170906170318/config.ini" --migration-list-format=json --migration-list-file="%plesk_dir%/var/modules/panel-migrator/sessions/20170906170318\migration-list-raw.json" --skip-services-checks --include-existing-subscriptions --overwrite --reload-source-data
  
  [INFO] Initialize Plesk Migrator
  [INFO] Target Plesk host: 203.0.113.2
  [ERROR] Internal Plesk Migrator error: '[Errno 13] Permission denied: u'C:\\Program Files (x86)\\Plesk\\version'', migration is aborted. See the traceback in debug log for more information.

Cause

Due to the enabled User Account Control: Admin Approval Mode for the built-in Administrator account policy, Plesk Migrator privileges elevation attempts are blocked.

This is a Plesk bug PMT-3847 which is planned to be fixed in future product updates.

Resolution

1. Connect to the server via RDP.

2. Modify the security policy:

   If the server is not in domain

   1. Open Command Prompt.

   2. Open Local Security Policy:

      C:\> secpol.msc

   3. Navigate to Security Settings > Local Policies > Security Options

   4. Double-click on the User Account Control: Admin Approval Mode for the built-in Administrator policy, select the Disabled option and click on the OK button:

      

   If the server is in domain

   1. Open Command Prompt.

   2. Enter gpedit.msc and press the Enter button

   3. Navigate the console tree to Local Computer Policy\Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options

   4. Double-click on the User Account Control: Admin Approval Mode for the built-in Administrator policy, select the Disabled option and click on the OK button:

      

   5. Go back to Command Prompt and apply updated policy by executing the following command:

      C:\> gpupdate
      
      Updating policy...
      
      Computer Policy update has completed successfully.
      User Policy update has completed successfully.

Additional information

UAC Group Policy Settings and Registry Key Settings | Group Policy settings