Ubuntu 24.04下，APT源的格式相较之前有变动，之前的经验是不可用的。

路径： /etc/apt/sources.list.d/ubuntu.sources

打开这个路径：

cd /etc/apt/sources.list.d
sudo cp ubuntu.sources ubuntu.sources_cp
sudo rm -rf ubuntu.sources
sudo vim ubuntu.sources

按i键，粘贴以下代码：

Types: deb
URIs: https://mirrors.ustc.edu.cn/ubuntu/
Suites: noble noble-updates noble-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

Types: deb
URIs: https://mirrors.aliyun.com/ubuntu/
Suites: noble noble-updates noble-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

Types: deb
URIs: https://repo.huaweicloud.com/ubuntu/
Suites: noble noble-updates noble-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

Types: deb
URIS: https://mirrors.tuna.tsinghua.edu.cn/ubuntu/
Suites: noble noble-updates noble-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

包含了4个国内源。如需改动，只需改URIS那行，其他完全不需要动。

保存并退出vim。

:wq!

执行命令使得国内源生效：

sudo apt update
sudo apt upgrade

完成。