This page is about howto get ride of the error which says "W: GPG error: testing Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 010908312D230C5F > W: You may want to run apt-get update to correct these problems" while updating your system with apt-get. Most of the time you get this error if the pubkey is not available on the debian server from were you are downloading your packages.

More detailed info are present on SecureApt (interesting things starting from How apt uses Release.gpg) . Please understand what you are doing first.

after running the first command you may get an output similar to this one

gpg: requesting key 2D230C5F from hkp server gpg: key 2D230C5F: public key "Debian Archive Automatic Signing Key (2006) < >" imported gpg: no ultimately trusted keys found gpg: Total number processed: 1 gpg:               imported: 1

and then when you run the second command you may get this output:

gpg: no ultimately trusted keys found OK

if you get the above output's that means a proper key hasn't been found yet just repeat first 2 steps. and then you can update your packages once every thing is perfect.