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I can not install anything through 'Ubuntu Software Center'. The system refuse to accept the su password that it accepts in terminal. It might be relevant that I've had change the user's password a while ago but do not remember the old password. Also I have added the user as a sudoer in /etc/sudoers.

Please notice that I have this authentication problem only in Gnome, where I get

Your authentication attempt was unsuccessful. Please try again.

whenever I enter my user password in the authentication window. I can use the very same password of the same user to install the package from terminal. So basically I'm limited to terminal for all my root activity.

How can I resolve this annoying problem?


share|improve this question

Use the new sudoer's password to authenticate in the Ubuntu Software Center. The new sudoer's password is not a problem since you can change it with the passwd command :

wbad_prompt-$ su

<login as root>

root_prompt-# sudo passwd new_sudoer_username

<write new sudoer's password twice>

root_prompt-# exit

<log out as root>

wbad_prompt-$ exit
share|improve this answer
usin 'su', I get 'su: Authentication failure'. However I can use 'sudo su' to become root. Then I proceed with the rest of your suggestions but it did not solve the problem. – wbad Jan 10 '13 at 0:00

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