After an upgrade of raspbian I rebooted the system and it printed the following message:

"mounting /dev/mmcblk0p2 on /root failed: No such device"

After that an emergency shell (busybox) appeared. When I mounted the partition it worked without any problems. I changed the filesystem to vfat because I thought some kernel modules were missing, but it didn't help.

How can I debug this?

  • 1
    Probably quickest to reimage and start again.
    – joan
    Commented Aug 10, 2022 at 13:28
  • What OS are you using? Raspberry Pi OS hasn't used /dev/mmcblk0p2 for years! Did you fiddle with cmdline.txt?
    – Milliways
    Commented Aug 10, 2022 at 23:51

1 Answer 1


Thanks to joan, I compared my system to a standard image and realized, that I forgot to change the rootfstype in /boot/cmdline.txt

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.