I ran into a similar situation with Ubuntu 14.04.3 during an exercise to have complete un-attended system provisioning of VM's and Baremetal The work-around helped by adding--> d-i preseed/early_command string umount /media
I ran into a similar situation with Ubuntu 14.04.3 during an exercise to have complete un-attended system provisioning of VM's and Baremetal early_command string umount /media
The work-around helped by adding--> d-i preseed/