参考：https://blog.csdn.net/qq_30290661/article/details/103386997
修改/etc/apt/sources.list，去掉自带的源，添加如下源：
deb http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ buster main contrib non-free rpi deb-src http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ buster main contrib non-free rpi
修改：/etc/apt/sources.list.d/raspi.list，去掉自带的源，添加如下源：
deb http://mirrors.tuna.tsinghua.edu.cn/raspberrypi/ buster main ui deb-src http://mirrors.tuna.tsinghua.edu.cn/raspberrypi/ buster main ui
最后：
sudo apt-get update sudo apt-get upgrade
原文：https://www.cnblogs.com/xbit/p/12057523.html