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I just installed Ubuntu 12.04. Then I changed my own user profile to not require a password and log me in automatically. What happened is, I'm still asked for a password once the desktop diplays. Once I'm in, I find my password is not accepted when I'm trying to install an application or make changes to user accounts.

I'm still listed as an administrator, so I figure something must have happened to my password. My question is, why is my password accepted for logging in as a user, but not to do administrator stuff? It's the same password, isn't it? The one I set when I installed Ubuntu.

I tried resetting the password at the root shell prompt (accessed via recovery mode), but I only get an error, with the result "Password unchanged".

Help! Is there something else I can do to avoid completely reinstalling Ubuntu?

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2 Answers 2

I had the same issue. Changing, just a bit, Robin's answer solved the problem...

I've changed a little the steps suggested on: http://www.psychocats.net/ubuntu/fixsudo

  1. Boot in recovery mode as root
  2. Enter the command: mount -o rw,remount /
  3. Enter the command: groupadd admin
  4. Enter the command: adduser username admin
  5. Enter the command: sudo nano /etc/sudoers
  6. Right below root ALL=(ALL:ALL) ALL add this line username ALL=(ALL:ALL) ALL
  7. Press Ctrl+X and answer 'y' to save the changes
  8. Enter the command: passwd username
  9. Enter your user's password
  10. Enter the command: exit
  11. Resume normal boot
  12. You 've made it!!!!

*where username is your actual username.

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The system has removed the user in question from the sudoer's file, which grants admin level permissions.

Instructions for fixing this are available at: http://www.psychocats.net/ubuntu/fixsudo

This page tells you how to get to the root prompt in recovery mode, and provides easy to follow, illustrated instructions for restoring a user to the "admin" group.

If during the process, you get a message telling you that the "admin" group does not exist (as I did) then enter the command: groupadd admin

Then re-do command to add the user to the "admin" group.

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Thanks for your reply. It is a relief to learn the cause of the problem. Further, as you warned, I did get the message that the "admin" group does not exist. However, when I typed "groupadd admin", I got the following message: groupadd: cannot lock /etc/group; try again later. (Before this I did also type the command to remount the filesystem as read-write.) –  jmatienza Apr 30 '12 at 13:46

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