Comment 1 for bug 732864

Thanks for reporting this bug and helping to make Ubuntu better.

To work around this and proceed, please first make sure there is no stuck useradd process:

  ps -ef | grep useradd
  ps -ef | grep groupadd

If either of those show results, then please kill the process (reply here if you need help with that).

Then please remove any stale lock files by doing:

  rm -f /etc/passwd.lock /etc/group.lock /etc/gshadow.lock

and then re-try your install or upgrade.