error Ubuntu update.

salam,

error update ubuntu:

W: GPG error: http://archive.canonical.com karmic Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key


solved:


gpg --keyserver keyserver.
ubuntu.com --recv 437D05B5; gpg --export --armor 437D05B5 | sudo apt-key add -; gpg --keyserver keyserver.ubuntu.com --recv 437D05B5; gpg --export --armor 437D05B5 | sudo apt-key add -; sudo apt-get upda