我正在升级 Ubuntu 18.04 系统。命令sudo do-release-upgrade失败并显示以下错误。此系统是 k8s 主控，但我这样做了sudo apt purge kubeadm kubectl kubelet。为什么它仍在寻求升级 k8s？
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B53DC80D13EDEF05
Fetched 0 B in 0s (0 B/s)
Hit http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit http://us.archive.ubuntu.com/ubuntu focal-backports InRelease
Hit http://security.ubuntu.com/ubuntu focal-security InRelease
Get:1 https://packages.cloud.google.com/apt kubernetes-xenial InRelease [8,993 B]
Hit https://apt.syncthing.net syncthing InRelease
Err https://packages.cloud.google.com/apt kubernetes-xenial InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B53DC80D13EDEF05
Fetched 0 B in 0s (0 B/s)
Error during update
A problem occurred during the update. This is usually some sort of
network problem, please check your network connection and retry.
Restoring original system state
Aborting
答案1
“为什么还想升级k8s呢？“
记住 apt 的工作原理：包来自人类指定的来源。
您删除了 k8s 软件包，但保留了 k8s 源。
因此，系统自然会寻找该来源。如果没有找到，就会向人类抛出错误。
您可以通过从 /etc/apt/sources.list.d/ 中的 apt 源中删除源来解决问题。或者，您也可以从“软件和更新”控制面板 -> 其他软件 -> 删除该源中删除源。