mount error

Code:

mount: mounting /dev/mmcblk0p9 on /root failed: No such device

Could not mount the partition /dev/mmcblk0p9.
This could also happen if the file system is not clean because of an operating system crash, an interrupted boot process, an improper shutdown, or unplugging of a removeable device without first unmounting or ejecting it. (filesystem = f2fs, error code = 255)

BusyBox v1.20.2 (Ubunti 1:1.20.0-8ubuntu1) built-in shell (ash)
Enter 'help' for a list of built-in commands.

(initramfs) _