There are times when running apt-get update in Ubuntu will result in error messages such as the following: [chris@server ~]$ sudo apt-get update Ign http://security.ubuntu.com trusty-security InRelease Get:1 http://security.ubuntu.com trusty-security Release.gpg [933 B] … Fetched 21.9 MB in 14s (1,537 kB/s) Reading package lists… Done W: GPG error: http://security.ubuntu.com trusty-security Release: The following signatures couldn’t … Continue reading Fix apt-get update “the following signatures couldn’t be verified because the public key is not available”