1. 报告 ： Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
E: The repository 'http://mirrors.163.com/debian bullseye InRelease' is not signed.
E: Failed to fetch http://mirrors.163.com/debian/dists/bullseye/InRelease Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
2. 网上介绍将源修改为HTTP方式，发现DEBIAN认为其不安全拒绝。
3 。最终解决方案：
下载ca-certificates和其依赖的openssl，然后再用HTTPS源即可（打破鸡生蛋、蛋生鸡问题）。
Debian -- 软件包下载地址选择 -- ca-certificates_20240203_all.deb