Why do I get GPG error when running apt-update for lenny-backports?

Question

Alright, so I'm trying to upgrade (if you could call it so) to lenny-backports as seen here, but I ran into this error when running apt-get update:

W: GPG error: http://backports.debian.org lenny-backports Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A*numbers and letters*A
W: You may want to run apt-get update to correct these problems

The line I added to sources.list is as follows:

deb      http://backports.debian.org/debian-backports lenny-backports main

And as Womble asked in previous question here is the version of debian-archive-keyring no matter what is that..

dpkg -l debian-archive-keyring
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name                       Version                    Description
+++-==========================-==========================-====================================================================
ii  debian-archive-keyring     2009.01.31                 GnuPG archive keys of the Debian archive

Answer 1

Your version of the debian-archive-keyring package is out of date. You need to upgrade it to the latest version available in lenny -- an apt-get install debian-archive-keyring should do the trick.

Answer 2

try this

gpg --keyserver hkp://subkeys.pgp.net --recv-keys 16BA136C
gpg --export 16BA136C | apt-key add -