When I do command sudo apt update, always get belowing errors: Err:1 http://archive.ubuntu.com/ubuntu bionic InRelease Could not connect to archive.ubuntu.com:80 (91.189.91.23). - connect (111: Connection refused) Could not connect to archive.ubuntu.
在安装更新时,即在运行命令行sudo apt-get update 或者运行更新管理器的时候,出现W: GPG 错误: W: GPG error: http://ppa.launchpad.net/ondrej/php/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4F4EA0AAE5267A6C 可
错误信息如下 W: GPG error: http://ppa.launchpad.net/ondrej/php/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4F4EA0AAE5267A6C 解决办法, 缺什么加什么 apt-key adv --recv-keys --keyserver keyse