Edited my sources.list and can no longer install packages

Hey there! Below is a copy of the default sources.list from a Linode running Buster:

deb http://mirrors.linode.com/debian buster main
deb-src http://mirrors.linode.com/debian buster main
deb http://mirrors.linode.com/debian-security buster/updates main
deb-src http://mirrors.linode.com/debian-security buster/updates main
# buster-updates, previously known as 'volatile'
deb http://mirrors.linode.com/debian buster-updates main
deb-src http://mirrors.linode.com/debian buster-updates main

Thank you!

This still fails for me as follows:

# apt-get update
Get:1 http://mirrors.linode.com/debian buster InRelease [122 kB]
Get:2 http://mirrors.linode.com/debian-security buster/updates InRelease [65.4 kB]
Get:3 http://mirrors.linode.com/debian buster-updates InRelease [51.9 kB]
Get:4 http://mirrors.linode.com/debian buster/main Sources [7,836 kB]
Ign:5 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu eoan InRelease
Get:6 http://mirrors.linode.com/debian buster/main i386 Packages [7,863 kB]
Err:7 http://ppa.launchpad.net/wireguard/wireguard/ubuntu eoan InRelease
  403  Forbidden [IP: 2001:67c:1560:8008::19 80]
Err:8 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu eoan Release
  404  Not Found [IP: 2001:67c:1560:8008::19 80]
Get:9 http://mirrors.linode.com/debian buster/main amd64 Packages [7,907 kB]
Get:10 http://mirrors.linode.com/debian buster/main Translation-en [5,968 kB]
Get:11 http://mirrors.linode.com/debian-security buster/updates/main Sources [199 kB]
Get:12 http://mirrors.linode.com/debian-security buster/updates/main i386 Packages [302 kB]
Get:13 http://mirrors.linode.com/debian-security buster/updates/main amd64 Packages [302 kB]
Get:14 http://mirrors.linode.com/debian-security buster/updates/main Translation-en [159 kB]
Get:15 http://mirrors.linode.com/debian buster-updates/main Sources [16.6 kB]
Get:16 http://mirrors.linode.com/debian buster-updates/main i386 Packages [15.2 kB]
Get:17 http://mirrors.linode.com/debian buster-updates/main amd64 Packages [15.2 kB]
Get:18 http://mirrors.linode.com/debian buster-updates/main Translation-en [13.9 kB]
Reading package lists... Done
E: Failed to fetch http://ppa.launchpad.net/wireguard/wireguard/ubuntu/dists/eoan/InRelease  403  Forbidden [IP: 2001:67c:1560:8008::19 80]
E: The repository 'http://ppa.launchpad.net/wireguard/wireguard/ubuntu eoan InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://ppa.launchpad.net/deadsnakes/ppa/ubuntu eoan Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Err:7 http://ppa.launchpad.net/wireguard/wireguard/ubuntu eoan InRelease
  403  Forbidden [IP: 2001:67c:1560:8008::19 80]
Err:8 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu eoan Release
  404  Not Found [IP: 2001:67c:1560:8008::19 80]

Both of these are errors from the server. The IPv6 address reported belongs to Canonical.

Apparently, launchpad.net (an Ubuntu-only development community) doesn't like your Debian client. Since launchpad.net is run by Canonical, they're probably refusing service to your non-Ubuntu client. It's their right…

A quick check of https://packages.debian.org/buster/net/ does not yield an entry for wireguard for Debian 10 (buster)…you probably knew that already. You have one of two choices:

1. upgrade to Debian 11 (bullseye) where wireguard is available; or
2. build it from source (which you can get from launchpad.net…beware that you may need to upgrade your kernel…in which option #1 is going to be much less pain).

-- sw