I just installed elementary OS 0.4.1 Loki on an iMac over the last weekend and everything went swimmingly well.
This AM when I try
sudo apt-get update,
I get this message:
W: The repository 'http://ppa.launchpad.net/versable/elementary-update/ubuntu xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. E: Failed to fetch http://ppa.launchpad.net/versable/elementary-update/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found E: Some index files failed to download. They have been ignored, or old ones used instead.