Alternatively, you can do what themultiboot pros(actual sysadmins) do, and invest in a hardware device that is dedicated for multiboot support such as anIODD drive. This is because a hardware solution is theONLY
Step 3:Take an external hard drive and connect it to your unbootable Mac system. Afterward, select a copy of your data files in theWondershare Recoverit Bootable Drive Windowand choose the external hard drive as the destination. Click the"Start Copy"button to begin copying your data from Mac...
As opposed to other applications, Rufus will request exclusive access to a drive, so if any other application is using it, you will get this kind of error, and you will need to find out which external application is the culprit. I could for instance be one of those (and this list is ...