Seems like the same thing as https://bugs.launchpad.net/ubuntu/+source/base-installer/+bug/313452
If so, the following workaround might be helpful, worked for me:
http://jaredforsyth.com/content/unetbootin-failed-unmount-cdrom
Seems like the same thing as https:/ /bugs.launchpad .net/ubuntu/ +source/ base-installer/ +bug/313452
If so, the following workaround might be helpful, worked for me:
http:// jaredforsyth. com/content/ unetbootin- failed- unmount- cdrom