403 우분투 저장소에 연결하려고 할 때 금지된 오류

저는 Ubuntu 14.04를 실행하고 있는데 sudo apt-get update몇 달 동안 실행하지 않았습니다.
로컬로 업데이트하려고 하면 /etc/apt/sources.list apt-get문제 없이 많은 저장소에 연결할 수 있지만 많은 저장소(전체의 15% 정도)가 이와 같은 오류를 반환합니다.

W: Failed to fetch http://nz.archive.ubuntu.com/ubuntu/dists/trusty-backports/multiverse/binary-i386/Packages  403  Forbidden

W: Some index files failed to download. They have been ignored, or old ones used instead.

내 컴퓨터가 마지막으로 연결된 이후 저장소 주소나 구성이 변경되었는지 궁금합니다. 그래서 전체 새로 고침을 수행한 다음 다시 설정하려면 몇 가지 프로세스를 거쳐야 합니까 /etc/apt/sources.list? 나는 다음과 같은 것을 생각하고 있었다

sudo apt-cache clean

하지만 나는 내 시스템이 지금보다 더 지루해지는 것을 원하지 않습니다.
이 문제를 어떻게 해결할 수 있나요 403 Forbidden error?

/etc/apt/sources.list의 현재 상태

# deb cdrom:[Ubuntu 14.04 LTS _Trusty Tahr_ - Release amd64 (20140417)]/ trusty main restricted

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

## Major bug fix updates produced after the final release of the
## distribution.
deb http://nz.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://nz.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://nz.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://nz.archive.ubuntu.com/ubuntu/ trusty universe
deb http://nz.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb-src http://nz.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://nz.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://nz.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://nz.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://nz.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://nz.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://nz.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu trusty-security main restricted
deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
deb-src http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
deb-src http://security.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