Replacing rootfs with ODROID C2 ubuntu does not work

[Lukanite]

I found your advice on getting Ubuntu on the A95X by using the ODROID C2 Ubuntu desktop image (ubuntu64-16.04lts-mate-odroid-c2-20161003), and tried it out - by extracting the files on the ext4 partition on the image and replacing the rootfs on the ext2 SD card I'm currently using.

However, when booting, it doesn't quite work; the serial console has the following output: Failed to switch root, dropping to a shell (full output at Pastebin)

It's a bit odd, however, since I can cd to /mnt and chroot there just fine, it just doesn't want to boot by itself. Any help would be appreciated!