The Plesk extension for Seafile does not allow password changes from within the Seafile administration or user’s settings pages, and prevents users from being added or removed.
You may have landed on this page because you attempted to execute either of those actions.
Please be aware that password resets and password changes should be executed through the regular Plesk user administration, and should not be executed through the Seafile instance for your domain.
The new password will synchronize from Plesk to Seafile, but would not synchronize from Seafile to Plesk — causing your users headaches.