Fix GPG error:....NO_PUBKEY

In Ubuntu, when we try to update the system we sometimes get error for GPG No_PUBKEY as follows:


W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ppa.launchpad.net lucid Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C1622487AAA521A8

This does no harm as its not a security issue but its very annoying everytime getting the same error. It happens because you don't have a suitable public key for a repository. Follow this steps to get rid of the error:


gpg --keyserver keyserver.ubuntu.com --recv 9BDB3D89CE49EC21

Which retrieves the key from ubuntu key server and then this:


gpg --export --armor 9BDB3D89CE49EC21 | sudo apt-key add -

Which adds the key to apt trusted keys. This will solve you problem.

The solution can be found here & here.