I have upgraded Ubuntu to 12.04 and now I have a problem in logging in after locking the screen: it says the password is incorrect even though I provide the valid password. I found a temporary solution by switching users and logging in again with the same user.

  • I'd report a bug if anybody can reproduce it. If you can reproduce it, drop a comment... – ζ-- May 2 '12 at 17:57
  • Having the same issue... on Ubuntu Mate 18.04... oddly this only occurred on my laptop after a clean install... I have installed other machines, including my desktop and there I've never had the issue... strange! I'll try the suggestion flagged as "accepted answer". – Manu Sep 10 '18 at 20:57

I had the same issue. It is likely the ownership is wrong for /etc/shadow (See section "gnome-screensaver authentication failure with incorrect /etc/shadow permissions" of this page).

You need to sudo chown root:shadow /etc/shadow then sudo chmod u=r,g=r /etc/shadow See this bug report.

The interesting question is "Why ownership changed?". Because I don't remember changing it.

  • Thanks it worked for me! For some unknown reason, the group ownership was "root" instead of "shadow" for /etc/shadow on my laptop. Resetting the group ownership to "shadow" solved the issue :-) – Manu Sep 11 '18 at 7:26

I could resolve this issue with the following permission changes:

sudo chown root:shadow /etc/gshadow
sudo chown root:shadow /etc/gshadow-
sudo chown root:shadow /etc/shadow
sudo chown root:shadow /etc/shadow-

Found here: http://ubuntuforums.org/showthread.php?t=1006366

  • Albeit less informative as the answer above, this is also a correct answer, thanks! ;-) – Manu Sep 11 '18 at 7:31

Had this problem on Ubuntu 16.04. Found the solution in http://ubuntuforums.org/showthread.php?t=1006366 (linked in fret's answer):

chmod 2755 /sbin/unix_chkpwd

In my case, unix_chkpwd had lost its setgid bit when I copied my entire filesystem to a new machine using tar.


I am using Ubuntu 14.04 and I had the same issue

By mistake I ran a chown on the root filesystem (Yikes!) and since then I started having the issue described here.

I ran the command given in oshobov's answer, but that did not work for me, but using my own account instead of root made it work.

sudo chown your-username:shadow /etc/shadow
  • 2
    /etc/shadow must not be owned by any other account than root! – guntbert Oct 5 '14 at 16:33

protected by Community Dec 24 '14 at 13:57

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

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