第一个问题
Ubuntu 20.04.4 由于没有公钥,无法验证下列签名: NO_PUBKEY 7EA0A9C3F273FCD8
解决方案:
$ cd /etc/apt/sources.list.d/
$ sudo rm -f docker.list
$ sudo rm -f docker.list.save
$ sudo apt update
第二个问题
无法连接上 cn.archive.ubuntu.com:80 (123.129.214.98)。 - connect (111: 拒绝连接)
1.sudo cp /etc/apt/sources.list /etc/apt/sources_default.list
2.sudo gedit /etc/apt/sources.list
deb https://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb https://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
# deb https://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
# deb-src https://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb https://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse