"error unmounting /dev/sda1:target is busy" when I try to resize a partition [duplicate]

Solution 1:

  1. The Key next to the partition in gparted indicates that the drive is mounted (in use). So, you need to "unmount" them to be resized.
  2. You cannot unmount root partition if you are booting from it.
  3. It is usually better to do partition changes from a Live media/pendrive

Hope it helps.