Debian apt-get errors about gpg key

If during your apt activity you are getting some errors like this:  

W: GPG error: etch Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 9AA38DCD55BE302B

Try to add the key from keyserver specifying the key id and you should be ok

~# gpg --keyserver --recv-key  9AA38DCD55BE302B ~# gpg -a --export 9AA38DCD55BE302B | apt-key add -