GPG error: http://extras.ubuntu.com trusty Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192

It’s a known procedure, but I am posting here because is something I have to do from time to time:

gpg --keyserver keyserver.ubuntu.com --recv 3E5C1192
gpg --export --armor 3E5C1192 | sudo apt-key add -
sudo apt-get update