Ubuntu - Fix "W: GPG..." key error
Sometimes, You run "sudo apt-get update" and get this kind of error: W: GPG error: http://extras.ubuntu.com precise Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C119 2 It is because your apt misses that public key. So, to fix this issue, just run the following command to add the need key: $ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 16126D3A3E5C1192 then run update again: $ sudo apt-get update If the above method does not work, try this: $ sudo apt-get clean $ cd /var/lib/apt $ sudo mv lists lists.old $ sudo mkdir -p lists/partial $ sudo apt-get clean $ sudo apt-get update