If you’ve ever used the a package or repository from the Ubuntu Personal Pakacge Archive, you may have receive an error when each time you use apt-get. The error looks something like this.

W: GPG error: http://ppa.launchpad.net lucid Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D8D75E403EBCE749

 

It’s a simple one line fix, the one line fetches the GPG key for the repository from keyserver.ubuntu.com:

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys D8D75E403EBCE749

Once you’ve run this command, apt-get will no longer report errors with finding the correct GPG public key.