NO_PUBKEY / GPG error

Who use linux systems may encounter the following error:

W: GPG error: ftp://ftp.debian.org/ testing Release:       
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY EB563F93142986CE

W: There is no public key available for the following key IDs:      
EB563F93142986CE

The ID is different everytime but the solution is always the same:

# gpg --keyserver keyserver.ubuntu.com --recv-key YOURSEGNALEDID
# gpg -a --export YOURSEGNALEDID | sudo apt-key add -

Easy.

Enjoy!