If you have appended this to the end of the grub command line to change a lost password:
init=/bin/bash Ubuntu and you get this error.
[email protected]:~# passwd jason Enter new UNIX password: Retype new UNIX password: passwd: Authentication token manipulation error passwd: password unchanged
Then you may fix this by remounting the filesystem read-write.
Accomplish this by typing this at the prompt.
mount -rw -o remount /
This will remount the root filesystem read-write and allow changes to the files on the filesystem. That is how easy it is to fix this problem.
Then you should be able to restart your machine by executing:
shutdown -r now.