Looks like when you updated the content of the admin/db-updater.php file, you accidentally left a space at the very beginning of the file, which is causing the error. Remove that stray space and all should be good.
This free Support Forum relies on contributions from our support staffs and fellow Graphene themes users. While we endeavour to provide adequate and timely support, due to its voluntary nature responses are not guaranteed and may be delayed.
If you require urgent assistance, you may like to consider our Priority Support option.