Cannot restore a subscription from backup: System user update is failed: The user johndoe already exists

Symptoms

• Cannot restore a subscription from backup: 

  PLESK_ERROR: Execution of "C:\Program Files (x86)\Plesk\bin\domain.exe" --update example.com -guid F4A1C96E-693D-4378-94FD-58CF0F0498CB -creation-date 2016-07-21 -description "" -hosting true -hst_type phys -do-not-apply-skeleton -ip 203.0.113.2 -www-root httpdocs -login checkmail -passwd "" -passwd_type sym -shell "Login Enabled" -ignore-nonexistent-options failed with return code 1. Stderr is An error occurred during domain update: An error occurred during changing of hosting settings: System user update is failed: The user johndoe already exists.

• There is a mail account with the same name as the main system user johndoe@example.com

Cause

This is Plesk bug #PPPM-9878 which is planned to be fixed in future Plesk updates.

Resolution

As a workaround, 

1. Connect to the server via RDP
2. Remove the system user manually.
3. Login to Plesk and create example.com subscription manually with the system user jhondoe in Plesk manually at Plesk > Subscriptions > Add Subscription.
4. Start the restoration of the subscription from the backup.