Debian系统无法升级的一个原因
我用WSL安装了Debian 12 系统，无法升级，出现以下错误：
yong@DESKTOP-D1TMKU9:~$ sudo apt update Ign:1 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm InRelease Ign:2 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-updates InRelease Ign:3 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-backports InRelease Ign:4 https://mirrors.tuna.tsinghua.edu.cn/debian-security bookworm-security InRelease Ign:1 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm InRelease Ign:2 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-updates InRelease Ign:3 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-backports InRelease Ign:4 https://mirrors.tuna.tsinghua.edu.cn/debian-security bookworm-security InRelease Ign:1 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm InRelease Ign:2 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-updates InRelease Ign:3 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-backports InRelease Ign:4 https://mirrors.tuna.tsinghua.edu.cn/debian-security bookworm-security InRelease Err:1 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] Err:2 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-updates InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] Err:3 https://mirrors.tuna.tsinghua.edu.cn/debian bookworm-backports InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] Err:4 https://mirrors.tuna.tsinghua.edu.cn/debian-security bookworm-security InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] Reading package lists... Done Building dependency tree... Done All packages are up to date. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-updates/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-backports/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian-security/dists/bookworm-security/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-updates/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-backports/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian-security/dists/bookworm-security/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-updates/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-backports/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian-security/dists/bookworm-security/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-updates/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-backports/InRelease: No system certificates available. Try installing ca-certificates. W: https://mirrors.tuna.tsinghua.edu.cn/debian-security/dists/bookworm-security/InRelease: No system certificates available. Try installing ca-certificates. W: Failed to fetch https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm/InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] W: Failed to fetch https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-updates/InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] W: Failed to fetch https://mirrors.tuna.tsinghua.edu.cn/debian/dists/bookworm-backports/InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] W: Failed to fetch https://mirrors.tuna.tsinghua.edu.cn/debian-security/dists/bookworm-security/InRelease Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 101.6.15.130 443] W: Some index files failed to download. They have been ignored, or old ones used instead.
好像是认证出现问题，网上搜了一阵，也没有找到明确的解决方法。无意间扫到在清华源有这么一句话：
Debian Buster 以上版本默认支持 HTTPS 源。如果遇到无法拉取 HTTPS 源的情况，请先使用 HTTP 源并安装：
sudo apt install apt-transport-https ca-certificates
于是，打开 /etc/apt/sources.list 把 https 换成 http，再运行 sudo apt update 果然可以了，按照提示安装上述软件，果然可以使用了。
随后，再把 http 改为 https，再次更新，果然没有问题了。
