ubuntu执行sudo apt update 出现问题

问题描述：

Reading package lists... Done
E: Failed to fetch https://mirrors.ustc.edu.cn/ubuntu-ports/dists/focal/main/binary-amd64/Packages  404  Not Found [IP: 202.38.95.110 443]
E: Failed to fetch https://mirrors.ustc.edu.cn/ubuntu-ports/dists/focal-updates/main/binary-amd64/Packages  404  Not Found [IP: 202.38.95.110 443]
E: Failed to fetch https://mirrors.ustc.edu.cn/ubuntu-ports/dists/focal-backports/main/binary-amd64/Packages  404  Not Found [IP: 202.38.95.110 443]
E: Failed to fetch https://mirrors.ustc.edu.cn/ubuntu-ports/dists/focal-security/main/binary-amd64/Packages  404  Not Found [IP: 202.38.95.110 443]
E: Some index files failed to download. They have been ignored, or old ones used instead.

解决步骤：

1.检查当前架构配置

dpkg --print-architecture
dpkg --print-foreign-architectures

2. 如果显示了 amd64 架构，移除它

sudo dpkg --remove-architecture amd64

3. 检查并清理 sources.list 相关文件

检查所有软件源配置：

# 检查主配置文件
cat /etc/apt/sources.list

# 检查额外的源文件
ls /etc/apt/sources.list.d/
cat /etc/apt/sources.list.d/*

4. 完整重置 sources.list

创建正确的 ARM64 软件源配置：

sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup
sudo nano /etc/apt/sources.list

替换为以下内容：

deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal main restricted
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal-updates main restricted
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal universe
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal-updates universe
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal multiverse
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal-updates multiverse
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal-security main restricted
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal-security universe
deb https://mirrors.ustc.edu.cn/ubuntu-ports/ focal-security multiverse

5. 清理 APT 缓存并更新

sudo apt clean
sudo apt autoclean
sudo rm -rf /var/lib/apt/lists/*
sudo apt update

6. 如果仍有问题，检查 APT 配置

# 检查是否有强制架构的配置
sudo find /etc/apt -name "*.conf" -exec grep -l "amd64\|i386" {} \;

# 检查 APT 首选项
cat /etc/apt/preferences.d/* 2>/dev/null || echo "No preferences files"

7. 验证修复

运行以下命令确认只有 arm64 架构：

apt-cache policy
dpkg --print-architecture

如果以上步骤完成后仍有问题，可能需要检查是否有第三方软件源在 目录中配置了错误的架构。/etc/apt/sources.list.d/