Такая же проблема . Пытаюсь подключить диск с нтфс
Error mounting: mount exited with exit code 1: helper failed with:
mount: according to mtab, /dev/sdb1 is already mounted on /
# /etc/fstab: static file system information.
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc nodev,noexec,nosuid 0 0
/dev/sda1 / ext4 errors=remount-ro 0 1
# swap was on /dev/sda5 during installation
UUID=c8c5ac2c-8062-4ba1-9664-f1c55f037d72 none swap sw 0 0