Ubuntu 404 Not Found [IP:

出现 404  Not Found [IP: 或者出现 Failed to fetch http://….. 

一般是由于直接使用国外的源无法连接的原因导致的

建议换源试一试。

  执行备份命令：sudo cp /etc/apt/sources.list /etc/apt/sources.list.old

  打开文件：sudo vim /etc/apt/sources.list

  换源：复制源覆盖文件原来的内容（根据自己的网去尝试，选择最快的一个）

  更新源：sudo apt update        如果出现依赖问题-->sudo apt -f install 更新软件：sudo apt upgrade

 

阿里云开源镜像站： http://mirrors.aliyun.com/]

[清华大学：http://mirrors.tuna.tsinghua.edu.cn/  (IPv4+IPv6)]

[中科大：http://mirrors.ustc.edu.cn/  (IPv4+IPv6)]

#添加阿里源

deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse

 

deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse

 

deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse

 

deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse

 

deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse

 

deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse

 

deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse

 

deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse

 

deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

 

deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

 

#添加清华源

 

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse

 

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse

 

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse

 

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse

 

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse

 

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse

 

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse

 

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse multiverse

 

 

参考：https://www.cnblogs.com/Horizon-asd/p/12595723.html