I could not create customer, task "Create the user account" fails with the following error:
Client with login name 'customer1' already exists.
Client was not deleted completely from the system: some tasks were canceled.
Open System > Task Manager > Canceled Tasks to check if customer's removing task was canceled.
Restart all canceled tasks with "Remove the user account" name.
If canceled tasks were removed from the Task Manager history use the following command to remove the customer manually and then restart failed task:
/usr/local/psa/bin/client -r customer1