Lock screen - password incorrect

Question

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

Answer 1

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.