由于某种原因，当我尝试使用 sudo apt-get update 时，它会失败，并给我以下信息：
user@my-computer:~$ sudo apt-get update
Hit:1 http://us.archive.ubuntu.com/ubuntu xenial InRelease
Ign:2 http:/dl.google.com/linux/chrome/deb stable InRelease
Hit:3 http:/security.ubuntu.com/ubuntu xenial-security InRelease
Ign:4 http:/old-releases.ubuntu.com/ubuntu raring InRelease
Hit:5 http:/us.archive.ubuntu.com/ubuntu xenial-updates InRelease
Get:6 http:/deb.opera.com/opera stable InRelease [2,592 B]
Hit:7 http:/dl.google.com/linux/chrome/deb stable Release
Hit:8 http:/archive.canonical.com/ubuntu xenial InRelease
Hit:9 http:/ppa.launchpad.net/appgrid/stable/ubuntu xenial InRelease
Hit:10 http:/us.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit:12 http:/old-releases.ubuntu.com/ubuntu raring Release
Hit:13 http:/ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu xenial InRelease
Ign:14 http:/download.videolan.org/pub/debian/stable InRelease
Ign:6 http:/deb.opera.com/opera stable InRelease
Hit:11 http:/screenshots.getdeb.net xenial-getdeb InRelease
Hit:15 http:/ppa.launchpad.net/videolan/stable-daily/ubuntu xenial InRelease
Hit:17 http:/ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease
Hit:18 http:/download.videolan.org/pub/debian/stable Release
Hit:19 http:/ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu xenial InRelease
Fetched 2,592 B in 1s (1,580 B/s)
/usr/share/appgrid/appdata/helpers.py:9: PyGIWarning: Soup was imported without specifying a version first. Use gi.require_version('Soup', '2.4') before import to ensure that the right version gets loaded.
from gi.repository import GLib, GObject, Soup
Reading package lists...
W: GPG error: http:/deb.opera.com/opera stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 63F7D4AFF6D61D45
W: The repository 'http:/deb.opera.com/opera stable InRelease' is not signed.
W: There is no public key available for the following key IDs: 63F7D4AFF6D61D45
W: http:/dl.google.com/linux/chrome/deb/dists/stable/Release.gpg: Signature by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 uses weak digest algorithm (SHA1)
W: http:/dl.google.com/linux/chrome/deb/dists/stable/Release.gpg: Signature by key 3B068FB4789ABE4AEFA3BB491397BC53640DB551 uses weak digest algorithm (SHA1)
W: http:/download.videolan.org/pub/debian/stable/Release.gpg: Signature by key 8F0845FE77B16294429A79346BCA5E4DB84288D9 uses weak digest algorithm (SHA1)
有什么建议么？
答案1
实际上，它并没有失败。W:代表非致命警告，您可以不用担心它。
修复公钥错误：
wget -O - http://deb.opera.com/archive.key | sudo apt-key add -
/usr/share/appgrid/appdata/helpers.py引发错误的原因是应用程序存在问题，而不是恰当的问题，您可以轻松忽略它。
最后，这个问题weak digest algorithm无法修复，因为这是开发人员的问题，而不是你的问题。
希望这能使事情明朗。