部分小鸡估计是系统镜像问题，在执行升级，也就是 apt-get update的时候会报错，如下

这个问题其实就是更新源的地址出错了，换了就行

1.备份一下原版的sources.list文件，其实不备份也行，看喜好

mv /etc/apt/sources.list /etc/apt/sources.list.old

2.替换源。
如果你的是国外小机，直接复制下面整段代码运行

cat > /etc/apt/sources.list << EOF
deb http://deb.debian.org/debian/ bullseye main contrib non-free
deb-src http://deb.debian.org/debian/ bullseye main contrib non-free

deb http://deb.debian.org/debian/ bullseye-updates main contrib non-free
deb-src http://deb.debian.org/debian/ bullseye-updates main contrib non-free

deb http://deb.debian.org/debian/ bullseye-backports main contrib non-free
deb-src http://deb.debian.org/debian/ bullseye-backports main contrib non-free

deb http://deb.debian.org/debian-security/ bullseye-security main contrib non-free
deb-src http://deb.debian.org/debian-security/ bullseye-security main contrib non-free
EOF

如果你的是国内小鸡，用这段代码，这个是国内阿里云的

cat > /etc/apt/sources.list << EOF
deb http://mirrors.cloud.aliyuncs.com/debian/ bullseye main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian/ bullseye main contrib non-free

deb http://mirrors.cloud.aliyuncs.com/debian/ bullseye-updates main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian/ bullseye-updates main contrib non-free

deb http://mirrors.cloud.aliyuncs.com/debian/ bullseye-backports main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian/ bullseye-backports main contrib non-free

deb http://mirrors.cloud.aliyuncs.com/debian/ bullseye-proposed-updates main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian/ bullseye-proposed-updates main contrib non-free

deb http://mirrors.cloud.aliyuncs.com/debian-security/ bullseye-security main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian-security/ bullseye-security main contrib non-free
EOF

3.应该好了，apt-get update试试