"Partition failed with error: Couldn't unmount drive" I am trying to create a new partition so I can install Windows through Boot Camp. I boot into recovery mode using my Recovery Assistant USB and no matter what I do, when I try to resize my drive and create a new partition, I get this error. What am I doing wrong?
Have you tried repartitioning with Boot Camp (just go through the Boot Camp process normally)? You shouldn't have to repartition manually in the first place.