Comment 0 for bug 1629646

I just noticed that following files in /etc/apt/soures.list.d have wrong urls which causes Elementary Loki updates not be delivered fine.

-elementary.list-
deb http://ppa.launchpad.net/elementary-os/stable/ubuntu loki main
deb-src http://ppa.launchpad.net/elementary-os/stable/ubuntu loki main

-patches.list-
deb http://ppa.launchpad.net/elementary-os/os-patches/ubuntu loki main
deb-src http://ppa.launchpad.net/elementary-os/os-patches/ubuntu loki main

Which needs to be updated as follows,

-elementary.list-
deb http://ppa.launchpad.net/elementary-os/stable/ubuntu xenial main
deb-src http://ppa.launchpad.net/elementary-os/stable/ubuntu xenial main

-patches.list-
deb http://ppa.launchpad.net/elementary-os/os-patches/ubuntu xenial main
deb-src http://ppa.launchpad.net/elementary-os/os-patches/ubuntu xenial main

Here's the 'apt update' error before the fix,
---
Reading package lists... Done
W: The repository 'http://ppa.launchpad.net/elementary-os/stable/ubuntu loki 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.
W: The repository 'http://ppa.launchpad.net/elementary-os/os-patches/ubuntu loki 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/elementary-os/stable/ubuntu/dists/loki/main/binary-amd64/Packages 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/elementary-os/os-patches/ubuntu/dists/loki/main/source/Sources 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
---

This brought updates for many pantheon-specific stuff.
If this is common for other users too,they might be missing future updates from Elementary not even knowing so.