GPG error – Ubuntu apt-get

I was in a hurry to install the new version of “Picasa” on Ubuntu Gutsy Gibbon as previous version of Picasa didn’t allow me to upload the images to web directory. After adding the apt source to the sources.list, I ran aptitude update on my laptop and was hit by following error.

W: GPG error: https://dl.google.com testing Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY A040830F7FAC5991
W: You may want to run apt-get update to correct these problems

The error itself says what I should be doing to resolve the error. I found that the solution mentioned won’t work unless I resolve the previous GPG error. So, I was left with no other option other than fetching the GPG key and importing that to my system.

Here is the solution:

# sudo gpg --keyserver subkeys.pgp.net --recv-keys 7FAC5991; gpg --export 7FAC5991 | apt-key add --

ps: key used in the above command can be found in error : NO_PUBKEY A040830F7FAC5991 (last 8 char’s)

Following lines are the output resulted by the above command at console.

gpg: requesting key 7FAC5991 from hkp server subkeys.pgp.net
gpg: key 7FAC5991: “Google, Inc. Linux Package Signing Key ” not changed
gpg: Total number processed: 1
gpg: unchanged: 1
OK

Now, I could do aptitude update / even apt-get update without any issues and complete my picasa upgrade.