User's sudo password doesn't work in GUI dialogs

pl flag

I'm using Ubuntu 20.04. I have a user that allows me to do sudo operations. I can login with root without any problem.

I'm try to install a new keyboard language through the GUI (Settings etc.). This shows me a dialogue asking for my 'Administrator' password. My user's password doesn't work. What can I do?

Note: recall that I can do any operation form the terminal, as I can log in as root.

PD: I think I remember I need to add my user to a GUI sudoers group, but I'm not sure nor I know which group.

hr flag
Is the "user that allows me to do `sudo` operations" a member of the `sudo` *group*, or was it added as an individual entry in the sudoers file?
Martel avatar
pl flag
I have executed `groups $my_user` and I don't see `sudo`, therefore I imagine is the second option.
Martel avatar
pl flag
When the GUI displays the dialog that asks for the password, the user is 'Administrator', but I don't find that user in `/etc/passwd`
pl flag

I have solved the problem by adding my user to the sudo group: sudo usermod -aG sudo $my_user

The GUI authentication dialog uses PolicyKit, which is configured by default on Ubuntu to use membership of the sudo or admin Unix groups as a proxy for the LocalAuthority role:

$ sudo cat /etc/polkit-1/localauthority.conf.d/51-ubuntu-admin.conf

Users who obtain command-line sudo privileges via other means (i.e. individual entries or custom groups in /etc/sudoers) won't be recognized as having PolicyKit LocalAuthority privileges.

See also How can I make the sudo GUI work without the admin group?


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