E4 manager will only function properly if an account is in use by one computer at a time. If you receive this error your data can be recovered using the standard "Upload Recovery" options.
(1) log out of E4 manager from all accounts
(2) log into E4 manager on the computer where the 403 error occurred.
(3) follow the upload recovery steps in this article to retrieve the missing data.
Note: This restriction does not apply study specific "upload only" accounts.