Apt-get update error launchpad

Question

Whenever I apt-get update I get this error message at the end:

W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu/dists trusty 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/mc3man/trusty-media/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/mc3man/trusty-media/ubuntu/dists/dists/trusty/main/binary-amd64/Packages  404  Not Found
E: Failed to fetch http://ppa.launchpad.net/mc3man/trusty-media/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.

This is how my sources file looks like:

# deb http://mirrors.linode.com/ubuntu/ xenial main restricted

# deb http://mirrors.linode.com/ubuntu/ xenial-updates main restricted
# deb http://security.ubuntu.com/ubuntu xenial-security main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://mirrors.linode.com/ubuntu/ xenial main restricted
# deb-src http://mirrors.linode.com/ubuntu/ xenial main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://mirrors.linode.com/ubuntu/ xenial-updates main restricted
# deb-src http://mirrors.linode.com/ubuntu/ xenial-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://mirrors.linode.com/ubuntu/ xenial universe
# deb-src http://mirrors.linode.com/ubuntu/ xenial universe
deb http://mirrors.linode.com/ubuntu/ xenial-updates universe
# deb-src http://mirrors.linode.com/ubuntu/ xenial-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://mirrors.linode.com/ubuntu/ xenial multiverse
# deb-src http://mirrors.linode.com/ubuntu/ xenial multiverse
deb http://mirrors.linode.com/ubuntu/ xenial-updates multiverse
# deb-src http://mirrors.linode.com/ubuntu/ xenial-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://mirrors.linode.com/ubuntu/ xenial-backports main restricted universe multiverse
# deb-src http://mirrors.linode.com/ubuntu/ xenial-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu xenial partner
# deb-src http://archive.canonical.com/ubuntu xenial partner

deb http://security.ubuntu.com/ubuntu xenial-security main restricted
# deb-src http://security.ubuntu.com/ubuntu xenial-security main restricted
deb http://security.ubuntu.com/ubuntu xenial-security universe
# deb-src http://security.ubuntu.com/ubuntu xenial-security universe
deb http://security.ubuntu.com/ubuntu xenial-security multiverse
# deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse
deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable
# deb-src [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable
deb http://ppa.launchpad.net/mc3man/trusty-media/ubuntu/dists trusty main
# deb-src http://ppa.launchpad.net/chris-lea/libsodium/ubuntu xenial main

I have opened the PPA link in the web browser and there is no error reaching it.

Solution

You Distribution version is 16.04.

But as you see this PPA does not have any package for Xenial.

It only has packages for trusty (14.04) version of Ubuntu.

So please try this commands to remove this PPA:

sudo add-apt-repository -r ppa:mc3man/trusty-media
sudo apt update

Your problem should be solved.