Reading package lists... Done W: GPG error: http://ppa.launchpad.net trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D46F45428842CE5E
Still looking for the solution
Working Solution 2017/07
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keysD46F45428842CE5E
Solution
gpg --keyserver hkp://subkeys.pgp.net --recv-keys D46F45428842CE5E
gpg: requesting key 8842CE5E from hkp server subkeys.pgp.net
gpg: keyserver timed out
gpg: keyserver receive failed: keyserver error
Tags:
lists, gpg, http, ppa, launchpad, trusty, inrelease, signatures, couldn, verified, no_pubkey, ce, estill, sudo, apt, adv, keyserver, ubuntu, recv, hkp, subkeys, pgp, requesting, server, timed,