Ubuntu 18.04 apt-get update Errors

I have noticed that some of my packages are out of date, while apt claims that they are at the newest version. When I ran apt-get update, I got:

sudo apt-get update
Ign:1 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:2 http://repository.spotify.com stable InRelease                      
Hit:3 http://archive.ubuntu.com/ubuntu bionic InRelease                   
Ign:4 http://ppa.launchpad.net/b-eltzner/qpdfview/ubuntu bionic InRelease 
Hit:5 http://archive.ubuntu.com/ubuntu bionic-updates InRelease           
Hit:6 http://dl.google.com/linux/chrome/deb stable Release                

Ign:7 http://ppa.launchpad.net/george-edison55/cmake-3.x/ubuntu bionic InRelease
Hit:8 http://archive.ubuntu.com/ubuntu bionic-backports InRelease         
Hit:9 https://packages.microsoft.com/repos/vscode stable InRelease        
Hit:10 http://archive.ubuntu.com/ubuntu bionic-security InRelease         
Ign:11 http://ppa.launchpad.net/libreoffice/libreoffice-4-2/ubuntu bionic InRelease
Hit:12 http://ppa.launchpad.net/libreoffice/ppa/ubuntu bionic InRelease
Hit:13 http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu bionic InRelease
Ign:14 http://ppa.launchpad.net/tigerite/kernel/ubuntu bionic InRelease
Err:15 http://ppa.launchpad.net/b-eltzner/qpdfview/ubuntu bionic Release
  404  Not Found [IP: 91.189.95.83 80]

Err:16 http://ppa.launchpad.net/george-edison55/cmake-3.x/ubuntu bionic Release
  404  Not Found [IP: 91.189.95.83 80]
Err:17 http://ppa.launchpad.net/libreoffice/libreoffice-4-2/ubuntu bionic Release
  404  Not Found [IP: 91.189.95.83 80]
Err:18 http://ppa.launchpad.net/tigerite/kernel/ubuntu bionic Release     
  404  Not Found [IP: 91.189.95.83 80]
Reading package lists... Done                                             
E: The repository 'http://ppa.launchpad.net/b-eltzner/qpdfview/ubuntu bionic 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.

E: The repository 'http://ppa.launchpad.net/george-edison55/cmake-3.x/ubuntu bionic 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.
E: The repository 'http://ppa.launchpad.net/libreoffice/libreoffice-4-2/ubuntu bionic 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.
E: The repository 'http://ppa.launchpad.net/tigerite/kernel/ubuntu bionic 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.

I tried switching to different sources, running with --allow-unauthenticated and putting [trusted=yes] in front of everything in my sources.list. Any Ideas? My sources.list file is:

# deb cdrom:[Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725)]/ bionic main restricted

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


# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu bionic-updates main restricted
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-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://archive.ubuntu.com/ubuntu bionic universe
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic universe
deb http://archive.ubuntu.com/ubuntu bionic-updates universe
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-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://archive.ubuntu.com/ubuntu bionic multiverse
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://archive.ubuntu.com/ubuntu bionic-updates multiverse
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-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 [trusted=yes] http://archive.ubuntu.com/ubuntu bionic-backports main restricted universe multiverse
# deb-src http://de.archive.ubuntu.com/ubuntu/ bionic-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 bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner


deb http://archive.ubuntu.com/ubuntu bionic-security main restricted
# deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://archive.ubuntu.com/ubuntu bionic-security universe
# deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://archive.ubuntu.com/ubuntu bionic-security multiverse
# deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse

why don't you just open up software and sources :

and untick all the problematic sources,

then close software and sources (let it reload sources)

and try updating again.

you don't want to be using sources that don't match your distribution. first repair updates then one by one add versions of those PPA made for your distro and check that they don't break updates at each one.