Ubuntu: Fixing NO_PUBKEY error from apt-get

Posted by daniel on 11 January, 2015
Category General

This error is likely to appear when you added an extra repository to your sources (e.g., ppa.launchpad.net). In my case, it was due to Gnome3.

After running apt-get update, I received the following error message:

W: GPG error: http://ppa.launchpad.net trusty Release: The following signature couldn't be verified because the publix key is not available: NO_PUBKEY ≪SIGNATURE≫

Where ≪SIGNATURE≫ was the source signature and consisted of a hexadecimal representation of a large number.

The reason for that error is that I had added the repository, but not its public key. My system couldn't verify it was dealing with the right repository and not a fake one.

To fix it, we have to get the key from some source that we trust. In my case, I got it from Ubuntu. (I am using their system, so I kind of trust them anyway.)

The command to add the key is as follows:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys ≪SIGNATURE≫
sudo apt-get update

The last command I used just to confirm everything was right. ;)

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