Ubuntu 16.04 更新管理器错误

Question

每次我尝试执行软件更新时，我都会从软件管理器收到此错误：

W:GPG error: http://download.virtualbox.org/virtualbox/debian xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A2F683C52980AECF, W:The repository 'http://download.virtualbox.org/virtualbox/debian xenial InRelease' is not signed., W:Data from such a repository can't be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details., W:There is no public key available for the following key IDs:
A2F683C52980AECF  , W:The repository 'http://ppa.launchpad.net/blackmage/f.lux/ubuntu xenial Release' does not have a Release file., W:Data from such a repository can't be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details., W:The repository 'http://ppa.launchpad.net/gezakovacs/ppa/ubuntu xenial Release' does not have a Release file., W:Data from such a repository can't be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details., W:The repository 'http://ppa.launchpad.net/zeal-developers/ppa/ubuntu xenial Release' does not have a Release file., W:Data from such a repository can't be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details., W:http://deb.playonlinux.com/dists/trusty/InRelease: Signature by key 74F7358425EEB6176094C884E0F72778C4676186 uses weak digest algorithm (SHA1), W:http://liveusb.info/multisystem/depot/dists/all/Release.gpg: Signature by key 32027DE3D67157C45E69C0AE4E940D7FDD7FB8CC uses weak digest algorithm (SHA1), W:http://vagrant-deb.linestarve.com/dists/any/InRelease: Signature by key AD319E0F7CFFA38B4D9F6E55CE3F3DE92099F7A4 uses weak digest algorithm (SHA1), E:Failed to fetch http://ppa.launchpad.net/blackmage/f.lux/ubuntu/dists/xenial/main/source/Sources  404  Not Found, E:Failed to fetch http://ppa.launchpad.net/blackmage/f.lux/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found, E:Failed to fetch http://ppa.launchpad.net/gezakovacs/ppa/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found, E:Failed to fetch http://ppa.launchpad.net/zeal-developers/ppa/ubuntu/dists/xenial/main/source/Sources  404  Not Found, E:Failed to fetch http://ppa.launchpad.net/zeal-developers/ppa/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found, E:Some index files failed to download. They have been ignored, or old ones used instead.

以下是我尝试编辑我拥有的存储库时所显示内容的一些屏幕截图：

我不确定如何解决这个问题。

Answer 1

在命令行中输入以下内容：

wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox_2016.asc -O- | sudo apt-key add -

Answer 2

您需要删除升级前遗留的旧密钥。做：

sudo apt-key list

找到有问题的密钥（靠近“virtualbox”，在“pub”之后，xxx/KEYHERE）并执行：

sudo apt-key del KEYHERE

然后转到https://www.virtualbox.org/wiki/Linux_Downloads并按照“基于 Debian 的 Linux 发行版”中的说明进行操作

Answer 3

显然，您之前没有删除外部存储库就进行了系统升级。解决该问题的最简单方法是删除所有外部存储库并删除所有相关的公钥。完成此操作后，更新存储库 ( sudo apt-get update) 并检查现在是否一切都已修复...当不再发生错误时，您可以添加新的外部存储库，但仔细检查这些存储库是否“匹配 Xenial”...

根据您添加的存储库，更新存储库时仍然可能会出现“弱签名”警告 - 但您可以忽略它，因为它只是一条信息性消息。

gpg: Signature by key ... uses weak digest algorithm (SHA1)