每当我使用 sudo apt-get update 时，都会显示此错误：
Hit http://ppa.launchpad.net trusty/main amd64 Packages
Hit http://ppa.launchpad.net trusty/main i386 Packages
Hit http://ppa.launchpad.net trusty/main Translation-en
Hit http://ppa.launchpad.net trusty Release.gpg
Ign http://ppa.launchpad.net trusty Release
Ign http://ppa.launchpad.net trusty Release
Hit http://ppa.launchpad.net trusty Release
Hit http://ppa.launchpad.net trusty Release
Ign http://ppa.launchpad.net trusty/main amd64 Packages/DiffIndex
Ign http://ppa.launchpad.net trusty/main i386 Packages/DiffIndex
Hit http://ppa.launchpad.net trusty/main amd64 Packages
Hit http://ppa.launchpad.net trusty/main i386 Packages
Hit http://ppa.launchpad.net trusty/main amd64 Packages
Hit http://ppa.launchpad.net trusty/main i386 Packages
Err http://ppa.launchpad.net trusty/main Sources
403 Forbidden
Ign http://ppa.launchpad.net trusty/main Translation-en_US
Ign http://ppa.launchpad.net trusty/main Translation-en
Err http://ppa.launchpad.net trusty/main Sources
403 Forbidden
Err http://ppa.launchpad.net trusty/main amd64 Packages
403 Forbidden
Err http://ppa.launchpad.net trusty/main i386 Packages
403 Forbidden
Ign http://ppa.launchpad.net trusty/main Translation-en_US
Ign http://ppa.launchpad.net trusty/main Translation-en
Ign http://ppa.launchpad.net trusty/main Translation-en_US
Ign http://ppa.launchpad.net trusty/main Translation-en
Ign http://ppa.launchpad.net trusty/main Translation-en_US
Ign http://ppa.launchpad.net trusty/main Translation-en
Err http://ppa.launchpad.net trusty/main amd64 Packages
403 Forbidden
Err http://ppa.launchpad.net trusty/main i386 Packages
403 Forbidden
W: Failed to fetch http://ppa.launchpad.net/beineri/opt-qt57-trusty/ubuntu/dists/trusty/main/source/Sources 403 Forbidden
W: Failed to fetch http://ppa.launchpad.net/beineri/opt-qt57-xenial/ubuntu/dists/trusty/main/source/Sources 403 Forbidden
W: Failed to fetch http://ppa.launchpad.net/beineri/opt-qt57-xenial/ubuntu/dists/trusty/main/binary-amd64/Packages 403 Forbidden
W: Failed to fetch http://ppa.launchpad.net/beineri/opt-qt57-xenial/ubuntu/dists/trusty/main/binary-i386/Packages 403 Forbidden
W: Failed to fetch http://ppa.launchpad.net/beineri/opt-qt57-trusty/ubuntu/dists/trusty/main/binary-amd64/Packages 403 Forbidden
W: Failed to fetch http://ppa.launchpad.net/beineri/opt-qt57-trusty/ubuntu/dists/trusty/main/binary-i386/Packages 403 Forbidden
E: Some index files failed to download. They have been ignored, or old ones used instead.
==================================================================================这是我的 sources.list
# deb cdrom:[Ubuntu 14.04.4 LTS _Trusty Tahr_ - Release amd64 (20160217.1)]/ trusty main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ trusty main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-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://us.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty universe
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-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://us.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-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://us.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb http://us.archive.ubuntu.com/ubuntu/ trusty-security main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-security main restricted
deb http://us.archive.ubuntu.com/ubuntu/ trusty-security universe
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-security universe
deb http://us.archive.ubuntu.com/ubuntu/ trusty-security multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-security 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 trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty partner
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu trusty main
deb-src http://extras.ubuntu.com/ubuntu trusty main
deb http://us.archive.ubuntu.com/ubuntu/ trusty-proposed main universe multiverse restricted
## Update for Codeblock by Chunting
# deb http://apt.tt-solutions.com/ubuntu/
# deb http://apt.tt-solutions.com/ubuntu/
我该如何修复它？因为我想将我的操作系统从 Ubunt 14.04 升级到 16.04
答案1
我认为解决方案很简单 - 禁用不存在的存储库（opt-qt57-xenial和opt-qt57-trusty)：
sudo add-apt-repository -r ppa:beineri/opt-qt57-xenial
sudo add-apt-repository -r ppa:beineri/opt-qt57-trusty
sudo apt-get update
然后添加现有的Qt 5.7.1 PPA如果你需要这个版本：
sudo add-apt-repository ppa:beineri/opt-qt571-trusty
sudo apt-get update
sudo apt-get dist-upgrade