sudo apt-get install O php5-imagick dá erro “404 Not Found” e “E: Falha ao buscar…” [duplicado]

Question

Em exibição:

sudo apt-get install php5-imagick 

falhou e produziu saída incluindo isso no meio:

Get:7 http://us.archive.ubuntu.com/ubuntu/ trusty/main libavahi-common3 amd64 0.6.31-4ubuntu1 [21.7 kB]
Get:8 http://us.archive.ubuntu.com/ubuntu/ trusty/main libavahi-client3 amd64 0.6.31-4ubuntu1 [25.1 kB]
Err http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main libcups2 amd64 1.7.2-0ubuntu1.1
  404  Not Found [IP: 91.189.91.23 80]
Get:9 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main libcupsfilters1 amd64 1.0.52-0ubuntu1.2 [74.4 kB]
Get:10 http://us.archive.ubuntu.com/ubuntu/ trusty/main libfftw3-double3 amd64 3.3.3-7ubuntu3 [702 kB]
Err http://security.ubuntu.com/ubuntu/ trusty-security/main libcups2 amd64 1.7.2-0ubuntu1.1
  404  Not Found [IP: 91.189.92.200 80]
Err http://security.ubuntu.com/ubuntu/ trusty-security/main libcupsimage2 amd64 1.7.2-0ubuntu1.1
  404  Not Found [IP: 91.189.92.200 80]
Get:11 http://us.archive.ubuntu.com/ubuntu/ trusty/main libjasper1 amd64 1.900.1-14ubuntu3 [129 kB]
Get:12 http://us.archive.ubuntu.com/ubuntu/ trusty/main liblcms2-2 amd64 2.5-0ubuntu4 [132 kB]

e isso no final (referindo-se aos mesmos erros):

E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/c/cups/libcups2_1.7.2-0ubuntu1.1_amd64.deb  404  Not Found [IP: 91.189.92.200 80]
E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/c/cups/libcupsimage2_1.7.2-0ubuntu1.1_amd64.deb  404  Not Found [IP: 91.189.92.200 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

    

Answer 1

Outras perguntas estavam perto de duplicatas, mas tinham mensagens de erro diferentes e soluções muito complicadas, por isso parecia sensato postar essa pergunta e resposta para tentar manter as coisas simples.

No meu caso, foi resolvido simplesmente executando:

sudo apt-get update

Espero que os outros achem que é tão simples assim: -)