Linux Lite Update Error Log

[felix44860]

============ Log ===========

Hit:1 http://archive.canonical.com/ubuntu bionic InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu bionic InRelease
Hit:3 http://repository.spotify.com stable InRelease
Hit:4 http://us.archive.ubuntu.com/ubuntu bionic-security InRelease
Hit:5 http://us.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:6 https://repo.nordvpn.com/deb/nordvpn/debian stable InRelease
Hit:7 http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu bionic InRelease
Hit:8 http://us.archive.ubuntu.com/ubuntu bionic-backports InRelease
Hit:9 http://ppa.launchpad.net/teejee2008/ppa/ubuntu bionic InRelease
Get:10 https://mega.nz/linux/MEGAsync/xUbuntu_18.04 ./ InRelease [1,310 B]
Hit:11 http://mirror.unlockforus.com/linuxlite diamond InRelease
Err:10 https://mega.nz/linux/MEGAsync/xUbuntu_18.04 ./ InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 03C3AD3A7F068E5D
Reading package lists...
W: GPG error: https://mega.nz/linux/MEGAsync/xUbuntu_18.04 ./ InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 03C3AD3A7F068E5D
E: The repository 'https://mega.nz/linux/MEGAsync/xUbuntu_18.04 ./ InRelease' is not signed.