JIRA site import fails when synchronizing users and groups

Issue Summary

When importing a site backup into JIRA Cloud the users may face the following error when synchronizing users and groups:

The below exception is thrown by the import service:

ERROR: duplicate key value violates unique constraint "uk_user_name_dir_id"
  Detail: Key (lower_user_name, directory_id)=(username, 10000) already exisRunning new test!.

Workaround

There's no workaround at the moment but the migration support team can help on resolving this issue, please engage them here.